36 THE VOYAGE OF H.M.S. CHALLENGER. 



the hook-sacs, which are very short and contain numerous hooks disposed in the form of 

 a bunch. 



This larva was gathered by Macdonald, in lat. 3G° 1' N., and long. 15° 5' E. 



2. Clionopsis grandis, Boas (PI. II. figs, 7, 8). 



1885. Pneumodermon peronii, Verrill, Third Catalogue of the Mollusca recently added to the 



Fauna of the New England Coast, Trans. Conn. Acad. Arts 

 and Sci., vol. vi. p. 431. 



1886. Cliupsis grandis, Boas, Spolia atlantica, K. dansk. Vidensk. Selsk. Skriv., 6 Eaekke, 



Bd. iv. p. 170. 



Body a little more truncated at its posterior extremity than in the foregoing species. 

 Nuchal tentacles less developed. 



Foot. — The lateral lobes are a little larger and have the posterior extremity terminating 

 in an acute angle, so that a small part of this extremity is free; the folded tubercle, situated 

 behind and between these two lobes, is divided into two by a longitudinal median wrinkle. 



Fins short and wide, rounded at their free extremity. 



Posterior Gill. — Hexagonal crest of the same shape as in Clionopsis krohni ; 

 radiating crests longer. All these crests both radiating and hexagonal, and the latter 

 on its six sides, lateral, ventral and dorsal, bear fringes on each side at the base, those of 

 one side alternating with those of the other, whilst in Pneumonoderma fringes are 

 developed only on the dorsal and ventral sides of the quadrangular crest and on the 

 radial crests ; these fringes are simple rounded foldings, short, not contracted at the base 

 or subdivided, and resembling those of Pneumonoderma pacijicum. 



Radida. — The formula is 5 : 1 : 5 in the adult. 



Hook-sacs with about the same number of hooks as in Clionopsis krohni. 



Colour. — The animal is colourless ; the small brown spots are not so large as in the 

 foregoing species, and are chiefly numerous on the posterior part of the body and inside 

 the hexagonal crest of the gill. 



Length. — The specimen I have studied (from the North Atlantic) measured 22 mm.; 

 but one specimen observed by Boas (from the China Sea), reached a length of 30 cm. 



Habitat. — Australasian locality — China Sea (Copenhagen Museum). North Atlantic 

 localities — (l) Twenty miles south-east of Cape Hatteras, lat. 35° 0' N., long. 75° 0' W. 

 (U.S. National Museum and Brussels Museum); (2) lat. 39° 37' N., long. 71° 18' W., 

 collected by the steamer "Albatross" of the U.S. Fish Commission, August 1883 (Verrill, 

 as " Pneumodermon peronii"). 



I have not seen the type specimens of Boas in the Copenhagen Museum. The 

 above description and the figures are taken from a specimen from the North Atlantic, 

 sent to the Brussels Museum by the U.S. National Museum, under the name of 

 "Pneumodermon, n. sp. (?)" 



