| OCR Text |
Show 98 DR. J. 0. DE MAN ON A NEW FRESHWATER [Feb. 19, rather sharp, curved extremities that cross one another. The dactylus is somewhat granular along the inner border of its upper surface, but for the rest both fingers appear smooth and shining externally ; they are not furrowed, but each finger is marked with two or three longitudinal rows of small impressed punctures. On the inner surface, however, the dactylus appears at base distinctly furrowed just beneath the upper margin, but this groove also gradually changes, on the middle of the finger, into a row of punctures ; the immobile finger shows likewise on its inner surface ;i rather shallow longitudinal furrow that extends almost to the extremity. The dactylus is armed with about 20 or 21 small teeth, the fifth of which is the largest ; the first tooth is but little smaller, the three following gradually decrease in size; beyond the fifth 15 or 16 very small teeth extend nearly to the pointed tip, two or three of them being a little larger than the remaining. The immobile finger bears also 21 small teeth, the sixth of which is the largest aud nearly of the same size as the fifth tooth of the dactylus. The first four gradually increase iu size, the fifth is quite small, beyond the sixth there are three or four teeth smaller than the sixth, slightly decreasing in size and separated from one another by two or three very small teeth. The latter appear on both fingers, are somewhat compressed, with a straight or slightly arcuate upper edge; the larger teeth are more pointed. The smaller chela measures four-fifths of the other, but fully agrees with it in shape and characters. The ambulatory legs are of moderate length, those of the last pair being little longer than the cephalothorax is broad. The meropodites of the last pair are exactly three times as long as broad, also those of the penultimate pair, which are 20 mm. long and 6| m m . broad. Along their anterior edge the meropodites are covered with depressed acute granules, and they appear a little granular on their outer surface, especially near the anterior margin, except those of the last pair, which are quite smooth. The following two joints are likewise beset, on their fore edge, with small acute teeth or granules, and a few occur on the posterior margin of the propodites. The slender aud slightly arcuate dactylopodites taper regularly towards their pointed tips, and are longitudinally ridged both on their outer and inner surfaces. Those of the second and third pairs are furnished, at the base of their posterior margin, only with one spinuliform tooth, those of the fourth and fifth pairs with two or three ; several spinuliform teeth are observed along the anterior edge of these joints. In colour the cephalothorax is of an olive-green, that is lighter ou the gastric region and on the sternum than elsewhere. The postfrontal crest, the margins of the orbits and of the front, the granules of the antero-lateral margin, and the tooth of the epistome are yellow. The cbelipedes are greenish yellow, the ambulatory legs reddish yellow. Potamon (Potamonautes) aubryi H . M.-E. is a different species. |
