OCR Text |
Show 524 DR. G. HERBERT FOWLER ON THE [May 18, Scolopendra, Kef.-One on the neuropodium only; pigment dark red ; two lenses. Onisciformis, Esch.-Two on the notopodium, two on the neuropodium ; pigment yellow ; five lenses. These seem good diagnostic characters, but are unfortunately not entirely justified. Taking first the number and position of these organs, and accepting Vejdovsky"'s and Keferstein's account of vitrina and scolopendra respectively, the alleged presence of two " Flossenaugen" on each half of the parapodium in onisciformis is stated by Vejdovsky" to have been observed by Carpenter and Claparede \ and by Leuckart and Pagenstecher2. A reference to the original memoirs shows, however, that the first-named authors describe and figure one only on the notopodium, one on the neuropodium ; and that the German authors, describing a 2 m m . onisciformis under the name of quadrlcornis, describe and figure one only on the basal part of each parapodium. Busch 3 also, in describing young specimens, agrees with Leuckart and Pagenstecher. Tomopteris onisciformis, therefore, like T. vitrina, has apparently one " Flossen-auge " on the notopodium, one on the neuropodium, or two on each parapodium ; it has probably only one in young stages, and this only on certain parapodia. Taking next the question of the pigment, its colour, yellow, dark red, or brown, can hardly be reckoned diagnostic. Lastly, with regard to the question of the lenses-these appear, according to Greef4, who worked on fresh material at the Canary Islands, to be artificial products of the preservation fluids. Almost certainly, judged by a comparison of the figures, the five lenses attributed by Vejdovsky" to Leuckart and Pagenstecher's onisciformis are the same things as his " Augen-driise " cells, which appear to surround the pigment-cells in a surface view. There seems, therefore, to be no real specific distinction between Vejdovsky"'s vitrina and onisciformis (auctt.). In m y specimens of onisciformis the basal joint of the second cirrhi (Borstencirrhen) was sometimes longer, sometimes shorter than the first parapodium, and the eye-lenses were single-thus breaking down two more of his diagnostic criteria. It is possible, as Vejdovsky suggests, that T. scolopendra (Kef.) may be separate from T. onisciformis (? = Briarcea scolopendra, Quoy and Gaimard5); but it is always difficult, often impossible, to make certain of the " Flossenaugen'"' in preserved material, and conceivably scolopendra may prove a Mediterranean variety of onisciformis. The largest ' Eesearch' specimen measured 45-5 mm. in length; 1 Trans. Linnean Soc, xxiii. p. 59. 2 Arch. Anat. Physiol., 1858, p. 588. 3 Arch. Anat. Physiol., 1847, p. 180. 4 Zeitschrift wiss. Zoologie, xxxii. p. 237. 5 Ann. Sciences naturelles, x. p. 235. |