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Show 116 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. at Maldonado, in a lake that had been suddenly drained. There are .three specimens in the collection, none of them exceeding t?e length above g1ven. Mr. D · h er states 1· 0 his notes, that he belteves them to be full grown, arwm, owev , · Th b t' having taken them so repeatedly, in brooks,. of th~ same size. e .num er o spots var1· es f rom m' ne to twelve , and is sometimes d1fferent on the two Sides of the same specimen. . . . . . Independently of the spots, which at once ?haractenze th1~ spec1es, 1~ IS readily distinguished from the last by its teeth, whtch are more cuttmg than pomted, and in this respect rather departing from the character of the genus as esta-blished by Valenciennes. ] , LEBIAS LINEATA. Jen. PLATE XXII. Fig. 2. L. em-pore subelongato, subcompresso, viridescenti-fusco ; l~teribus li~~eis czrc.zter septem longitudinalibtt.S nigris, e maculis parvis subconfluentzbus formahs : dentzbus uniseriatis : caudali t·otttrtdata. D. 9; A. 9; C. 26, brevibus inclusis; P. 13; V. 6. LoNG. unc. 1. lin. 10. FoRM.-General form very similar to that of the Pcecilia decem-maculata. Slightly compressed; the depth one-fifth of the length ; the Length of the bead about four-and-a-half times in .the same. Head depressed: snout obtuse: mouth small; the commissure horizontal. Upper.J.aW very protractile; the lower one rather the longest, when the mouth is shut. Teeth form1~g a single closely-set series, somewhat compressed at bottom, the cutting edges tricusptd. Diameter of the eye nearly one-fourth the length of the head. Some large conspicuous pores on the lower jaw, pa&sing upwards io a series along the margin of the preopercle, not very near together, about eight or nine in all. Scales large, covering the head and all the pieces of the gill cover, as well as the body. About eight in the depth, and thirty in a longitudinal line from the gill to the caudal. One taken from the middle of the side of a semi-elliptic somewhat oblong form ; the free portion very finely striated, the basal with ten or twelve deeper-cut strire, these last nearly parallel, and of equal lengths. Lateral line faintly marked out by a dotted line; the first half in the third row oftlcales from the top, the last half in the fourth row. Dorsal commencing at exactly the middle point of the entire length. Anal opposite and similar. Caudal rounded. Pectorals small, about two-thirds the length of the head. Ventrals smaller, barely one-half of the same. The pectorals, when laid back, reach to the insertion of the ventra is; but the latter hardly attain to the anal. CoLoun.-Greenish-brown, with six or seven longitudinal dark lines on the sides, the lines apparently made up of spots for the most part confluent, but here and there not so, interrupting the continuity of the lines. All the fins pale dusky, without any spots or markings. Habitat, Maldonado. This new species of Lebias was taken by Mr. Darwin in the same lake at FISII. 117 Maldonado with the Pmtilia decem-maculata. There are several specimens in the collection, none of them exceeding the size above mentioned, and they have all the appearance of being full grown. Some have the lines of spots much more interrupted than others. 2. LEBIAS MULTIDENTATA. Jen. PLATE XXII. Fig. 3. L. corpore subelongato, subcomp1·esso, viridescenti-jusco ; lateribus fasciis angustis paucis longitudinalibm albidis obscurioribus: dentibus seriebus plurimis dispositis, omnibus tt·icuspidatis : caudali 1·otundatd. D. 9; A. 9; C. 26, brevibus inclusis; P. 13; V. 6. LoNG. unc. 3. lin. 2. FonM.-The general form and proportions of this species are extremely similar to those of the last; but it differs very remarkably in having behind the anterior row of tricuspid teeth, a band of minuter teeth above and below, all of which are also tricuspid, and similarly formed to those in front. Head one-fifth of the entire length; flattened on the crown. Jaws nearly equal; upper one very protractile. Scales large; about thitty·two in a longitudinal line, and eight in the depth; covering all the pieces of the opercle ; similar in form to those of the last species, but with the strire on the free portion finer and more numerous, the deep-cut basal strire also rather more numerous, amounting to about fourteen, and of unequal lengths, gradually increasing from the outermost to the middle ones. Lateral line similar; also the same pores on the lower jaw. Fins and finray-formnla similar: in both species the first and last rays of the dorsal and anal are simple, and shorter than the others. 'fhe anal perhaps terminates a little nearer the caudal than the dorsal does. CoLOUR.-( In spirits.) Greenish-brown, with very little appearance of markings in its present state. There is, however, some indication of an irregular scattered row of small black spots on each side, a little below the ridge of the back; also of two or three pale longitudinal narrow bands along the middle of the sides, which were probably more conspicuous in the living fish. The belly is yellow, and very tumid; but these are evidently characters merely indicative of the female sex. Habitat, Monte Video. This is another new species of Lebias taken by Mr. Darwin in fresh-water at Monte Video, if indeed it strictly belong to the genus ; but the circumstance of the teeth being in several rows, and in fact forming a complete band, is at variance with the generic characters as given by Cuvier. Tl1e teeth however being exactly of the same form as in the other species, and the general characters on the whole similar, 1 have not thought it expedient to erect it into a new genus. There is but one specimen in the collection, which appears to be a large female big with young. |