180 PERCY SLADEN TRUST EXPEDITION 



a kind of large chamber, around the eye ; at the proximal margin issues the tentacle (t), with 

 a broad, membranous base, the right being again slightly smaller than the left. On the base 

 some longitudinal muscular fibres are visible (mt) and a tiny nerve (nt) proceeds from the 

 top of the cerebral ganglion and innervates the tentacle. The cerebral ganglia (eg), to 

 the under side of which the pleural ganglia are attached, are juxtaposed, longitudinally 

 elongated, the right being very slightly larger than the left, and give rise to numerous 

 nerves, only a few of which are shown in the figure. 



The visceral nucleus (fig. 5) is compressed, elongated, showing at the ventral pole two 

 coils which are (in the only undamaged specimen) covered by the minute, delicate shell. 

 This shell is apparently very brittle, as I have not been able to see it, even in fragments, 

 in my specimens. The nucleus is, except for the coils, completely enveloped in the cutis, 

 forming here a large mantle, with an opening at the proximal side of the nucleus. I have 

 already described* the various organs within the mantle cavity, and now restrict myself 

 to giving a figure of the nucleus and its surrounding parts. Most conspicuous are the 

 gills (g) and, within the mantle cavity, the kidney (k), the walls of which show the same 

 structure as in Pterosoma. The osphradium, situated near the left margin of the mantle 

 opening, outside the row of small gills, exhibits a similar elongated shape. 



It may be noted here that the Cardiapoda placenta mentioned by E. A. Smitht 

 from Arron Island most likely is the same as my C. sublcevis, though Smith's specimen is 

 much larger (77 mm.). I found this suggestion merely on the radula, investigated by 

 me}, of the Challenger specimen, the central plate of which shows three exactly equal 

 cusps, just as in C. sublcevis ; moreover this last species may prove to be identical with 

 C. trachydermon. The same perhaps is to be said about the Cardiapoda placenta 

 recorded by Andre § from Amboina. The only information the author gives is a figure 

 of the radula, which shows the same character as mentioned above. 



14. Cardiapoda acuta Tesch. 



Stat, mm (l), nn (l), Desroches Atoll, Amirante Group. Two specimens, both females, 

 one of 20, the other of 55 mm. length. 



I have scarcely been able to discover further characteristic features of this species, 

 formerly described by me||. Both specimens, which seemed to be badly preserved, 

 possessed a stout proboscis and a long, slender tail, without any appendage ; this tail 

 is longer in my specimens than the stalk carrying the visceral nucleus, around which are 

 placed nearly 20 gills. Tubercles are found especially on the dorsal side ; they give a 

 rather rough appearance to the body. Gland-like spots of various shape are found all 

 over the body, in the same way as in the previous species. Yet it is distinguished at first 

 sight by its tail being devoid of appendages, and by its yellowish colour. Thus the animal, 

 though preserved in the same fluid (formol), forms a striking contrast with the tiny, 

 wholly transparent C. trachydermon and C. sublavis. I observed a similar difference in 

 the Siboga specimens of Cardiapoda. 



* I.e. pp. 75, 76. t Challenger Report, lxxii. Heteropoda, p. 26, tig. 2. 



% I.e. p. 25. 



§ Mollusques d'Amboine, Revue Suisse d. Zool. T. iv. p. 405, PI. xvn. fig. 2. 



|| I.e. p. 79, PI. xi. figs. 60—63. 



