REPORT ON THE PTEROPODA. 37 



I did not find any specific differences between the characters of this specimen and 

 those enumerated in Boas' description. If the comparison of living specimens from the 

 two localities confirms the identity of the two forms, as I believe it will, it will prove 

 that this species possesses an extensive geographical distribution. 



*3. Clionopsis modesta, n. sp. (PI III. fig. 2). 



Body a little more oval and less truncated at the extremities than in the two fore- 

 going species. Head small ; labial tentacles rather short. 



Foot rather large, with lateral lobes terminating behind in an acute angle ; folded 

 tubercle rather long. 



Fins contracted towards their distal extremity. 



Posterior Gill with scarcely distinct crests, and without foldings or fringes ; radiating 

 crests nearly obsolete. 



Radula and Hook-sacs not investigated in the single specimen collected. 



Colour. — Very pale rose, and without the small spots which are seen in the foregoing 

 species ; rectum visible as a dark brown line. 



Length, 3 mm. Notwithstanding the small size of this species it is not a larva, but 

 an adult specimen, the three cUiated rings having disappeared. 



Challenger Specimen. — Station 254, July 17, 1875 ; Yokohama to Honolulu ; 

 lat. 35° 13' N., long. 154° 43' W. 



In regard to the " two species of Pncumodermon " of Quoy and Gaimard, which Boas 

 thinks may possibly belong to Clionopsis, see p. 32. 



Pelagia alba of the same zoologists 1 (from Amboina ; length, 23 mm.) seems also 

 to have some resemblance to Clionopsis, in the general form of the body and the absence 

 of a lateral gill. The absence of a posterior gill in Quoy and Gaimard's figure is 

 explained by the slight development of this organ in most species of Clionopsis, and the 

 absence of the foot by the fact, that when its two anterior lobes are removed, the foot, 

 which possesses no posterior lobe, becomes almost indistinct. The enlargement of the 

 cephalic region in the above mentioned figure, quite agrees with the supposition that the 

 two anterior lobes of the foot were removed from one another in the figured specimen. 



Family III. Notobranc h^e i dm. 



188G. Notobranchxidx, Pelseneer, Description d'un nouveau genre de Pteropode Gyrunosome, 

 Bull. Sci. depart. Nord, p. 224. 



Characters. — Buccal appendages conical. Lateral gill absent. Posterior gill ; three 

 radiating crests (the dorsal one fringed) meeting posteriorly. Pigmented skin. 



1 Vnyage de decouvertes de 1' Astrolabe, Zoologie, t. ii. p. 392, pi. xxviii. figs. 7-9. 



