38 



The dorsal tentacles (fig. 1. & 2. a. a) are nearly one third of the length of the body, 

 and unusually thick (much thicker than in any Eolis known to me) at the base, and gradually 

 tapered towards the obtusely rounded extremity, smooth, only a little wrinkled transversely 

 by contraction, and without sheath. The labial tentacles (ibid. c. c) are 2 3 times shorter, 

 and 3 4 times thinner than the former, and pointed. As in the Eolis all the tentacles are 

 not retractile. The eye-spots were not perceived. Both the observed specimens had the 

 head elongated in front in a long projecting conical proboscis (d) consisting of 2 sharply 

 defined cylindrical divisions (the anterior thinner than the posterior), which it does not seem 

 that the animal can draw in; for in the living animal it was always held extended during the 

 creeping, which is a very slow and regular gliding progress. The falsely so-called gills (want- 

 ing all the conditions for breathing) are short, elongated conical, pointed smooth papillae 

 (fig. 3) of unequal size, which are situated somewhat irregularly along the projecting side- 

 borders of the mantle, and also within the same in greater or less number scattered over 

 the dorsal surface. A great number of these papillae had however fallen off in the specimens 

 examined. The genital aperture is situated on the right side, about in the anterior third 

 part of the length of the body, in the shape of a prominent roundish tubercle (e) from which 

 a tolerably large conical somewhat twisted and pointed penis protrudes. Some distance be- 

 hind the genital aperture, and in a line with it, or about in the middle of the length of the 

 body and on the same side, the anus is situated at the top of a circular smaller tubercle (f). 

 The 2 vertical lateral jaws, which extend in a longitudinal direction, are well deve- 

 loped, and occupy the fleshy sides of the bucal mass. They are (fig. 5. & 6) thin chitinous 

 plates of faint light horny-yellow (particularly in the anterior thicker part) transparent color 

 and irregular crescent-like shape (or rather remarkably like the shell of a Lima) externally 

 (fig. 5) somewhat convex particularly in the anterior part, and less so behind; internally (fig. 

 6) concave, and behind double as high as in front. Their upper and posterior very thin edge 

 is curved; the lower and in front somewhat thicker edge is nearly straight, and the foremost 

 edge truncated and strongly thickened, especially in the middle, where it terminates in a 

 % broad, projecting forward three-cornered process, pointed at the end, of horny or yellow brown 

 color, and resembling the ear-like process (auricula) of the cardinal edge of a Lima shell. 

 Just under this three cornered process, and consequently at the anterior ventral extremity, is 

 situated the apex of the jaw which is the most convex part of the jaw. To the apex is 

 attached the yellow-brown ligament (,,fulchrum" Alder & Hancock) which is a peg-shaped pro- 

 cess projecting downwards, and connecting both jaws. This peg-shaped process (ligament) 

 has at its basis a roundish enlargement, and when cut through, shews short transversal close 

 threads, that is, a ligamentary structure. When greatly magnified the jaw exhibits innumer- 

 able fine concentric growth-lines running parallel with the curved edge, and crossed by still 

 finer and closer lines running radially from the apex to the edge, forming a sort of threaded 

 structure. The lowest straight edge of the jaw is without doubt the cutting edge, although 

 it has here no teeth; for there is here no trace of ,,the strongly curved process which ex- 



