CYMBULIIDAE 287 



age, as specimens with a fin breadth of 10-22 mm. possessed the lobes. In the most 

 perfect specimens the outer edge of the fin takes a beautiful circular sweep and the white 

 surface is bordered with purple-brown. The specimens from Sts. 62 and 239 had minute 

 tubercles dotted all over the surface. 



This little-known species was collected by the Valdivia Expedition in 34° 14' 00" S, 

 80° 31' 00" E, somewhat north of New Amsterdam Island. 



Family CYMBULIIDAE 



Genus Cymbulia, Peron and Lesueur, 18 10 



Cymbulia peroni, Blainville, 1818. 



Cymbulia proboscidea, Gray, 1850. 



St. 81. 4-5 m. tow-net, 650 (-0) m. : 3 specimens and 4 conchae. 

 St. 86. 4-5 m. tow-net, 1000 (-0) m. : 3 specimens with conchae. 

 St. 87. Young-fish trawl, looo (-0) m.: i specimen with concha. 

 St. 257. Young-fish trawl, 100-150 (-0) m. : i concha. 



St. 268. Young-fish trawl, 100-150 (-0) m. : 13 specimens with 8 conchae; i m. tow-net, oblique, 

 73-0 m. : 17 specimens and 5 conchae ; i m. net, horizontal, 73 m. : 4 conchae. 



One of the above hauls was made north of Tristan da Cunha and the remainder between 

 Elephant Bay, West Africa, and Cape Town. Some of the animals were still attached to 

 their transparent slipper-like shells. A large specimen measured 30 mm. across the fins. 

 The ventral lobe of the fin is transparent and strengthened by two muscle bands placed side 

 by side, which become fused together in a point distally. The filament at the extremity, 

 which is shown in Boas' illustration (1886, Tab. 3, fig. 30), was missing in all the speci- 

 mens. The conchae measured 32-55 mm. in length. An exceptionally large concha 

 (St. 257) measured 66 mm. in length by 28 mm. in diameter. Tesch (1904) has described 

 a species of Cymbulia as C. sibogae, the deutoconch of which is characterized by the 

 acute dorsal extremity, by the straight rows of denticles on the aboral surface, by its 

 smaller size and shallower sinus at the ventral end. A concha from St. 86 had a pointed 

 extremity but the sinus at the ventral end was V-shaped. When, however, the conchae 

 are in poor condition and obviously beginning to dissolve away, they have a very thin 

 acute dorsal extremity and no tubercles. 



In this family, as in the last two genera, the tentacles are small and of equal size. The 

 pallial cavity is situated dorsally and there is no gill. The fins are very large and are con- 

 nected anteriorly with the proboscis and posteriorly with the apron. They are rather 

 thick and opaque, except at the edges where the muscles can be seen. The mantle is thin 

 and very extensive, and covers the transparent slipper-shaped deutoconch of horny 

 substance, which protects the viscera. The deutoconch succeeds a calcareous spiral 

 operculate larval shell. The jaws are not much developed. The radula, where present, 

 has the formula i-i-i . The gizzard contains four large and one small plate, as well as a 

 number of very small chitinous pieces. Vayssiere (1915, p. 173) says that the deutoconch 

 or protecting organ may be considered as a simple thickening of the mantle analogous 



