382 



DISCOVERY REPORTS 



excrescence, into which the presumed seminal channel also runs. The whole structure 

 is not unlike that of Amphitretus pelagicus figured by Sasaki (1917, fig. 2). The 

 likeness is heightened by the arrangement of the suckers and the absence of enlarged 

 suckers on this arm. On the other hand, I could find no paired suckers (such as 

 Sasaki figures) beyond the terminal swellings. The occurrence of this presumed 

 hectocotylus on the left side and its resemblance to that of Amphitretus is very 

 interesting. 



Remarks. The discovery of another species of this rare and remarkable form is an 



eminently satisfactory result. I propose to 

 treat its structure as fully as possible in a 

 forthcoming publication, and confine these 

 remarks to the specific status of the Dis- 

 covery specimen and one or two other 

 points. Vitreledonella is represented at pre- 

 sent by three species: V. alberti (Joubin, 

 1924, p. 38) was obtained at 33° ^o'-s^z' N, 

 i9°-i9° 16' W in 0-3500 mm., and at 

 35° 09' N, 21° 21' W in 0-3500 m.; V. 

 richardi (Joubin, 1918, p. i; 1924, p. 15) 

 was obtained at 30° 50' N, 25° 43' W in 

 5300 m.; V. ingeborgae (Joubin, 19296, 

 p. 16) was taken by the 'Dana' at 36° 36' N, 

 26° 14' W in 2000 m. V. transliicida is quite 

 distinct from all these species. The principal 

 differences are tabulated as shown on the 

 opposite page. 



Joubin (1924, p. 16) was evidently of two 

 minds as to whether these forms are pelagic 

 or benthic. He admits that, though the net 

 in which V. richardi was taken was lowered 

 to a great depth (cf. id. 1929 b), it might 

 have entered the net at an intermediate 

 depth. The present record conclusively 

 shows that it is a pelagic organism, though 

 it may possibly have a very wide vertical 

 range. Joubin {loc. cit. p. 18) makes the highly interesting observation that his V. 

 ingeborgae is incubatory. 



I shall discuss the affinities of this form more fully in a later publication. It is neces- 

 sary, however, to point out the close resemblance of the radula to that of the Octopodidae 

 and its divergence from that of Eledonella and Amphitretus, with which the genus is now 

 ranked (Tribe Ctenoglossa). 



Fig. 10. Vitreledofiella translucida. x 2. 



(Semi-diagrammatic.) See p. 380. 



