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



.sliort and thread-like. There is only one retractor muscle, which has four very short 

 roots inserted at the hind end of the body. The intestine exhibits five loose loops in the 

 right half of the body, and then passes into the close spiral with sometimes twelve double 

 coils. A thin contractile tube. Only one segmental organ, on the left side of the body. 

 The body is not more than 1 1 mm. in length. 



Habitat.— (a) H.M.S. " Porcupine," Station 6, 1870 ; lat. 48° 26' N., long. 9° 44' W. ; 

 358 fathoms. 



(b) H.M.S. "Porcupine," Station 47, 1869 ; lat. 59° 34' N., long. 7° 18' W.; 



542 fathoms. 



(c) H.M.S. ".Porcupine," Station 30, 1869; lat. 48° 50' N., long. 11° 9' W. ; 



725 fathoms. 

 (c/) H.M.S. "Triton," Station 10, August 24, 1882; lat. 59° 40' N., 

 long. 7° 21' W.; 516 fathoms. 



The intestine contained numerous Globigerina shells, besides sand and fine debris of 

 mussel-shells and of the calcareous plates of Echiuodermata. 



This species occupies a position only just within the genus Phascolion, being indeed 

 a sort of connecting link with the genus Phascolosoma. It may be ranked as a species 

 of Phascolion on account of ( 1 ) the disappearance of one of the two segmental organs 

 and the fixing of the remaining one by means of a mesentery, (2) the coalescence of the 

 retractors of the proboscis and the shifting of their insertion to the hind end of the bodj^, 

 (3) the smaller size of the testacies, (4) the larger size of the eggs, (5) the development of 

 the ordinary dermal papillse into attaching papillae, (6) the partial unwinding of the intes- 

 tinal spiral into loose coils. On the other hand, since the intestinal spiral may still have 

 as many as twelve double coils, the species may be claimed, as Koren and Danielssen 

 have done, for the genus Phascolosoma. On the whole, however, there seems more 

 reason, as we have indicated, to refer the species to the genus Phascolion. 



15. Phascolion Intense,^ n. sp. (PL IV. figs. 22, 23). 



The skin is thin and without attaching papillae (Haftpapilleu) on the posterior part 

 of the body. The whole body and proboscis studded with numerous scattered skin glands. 

 These protrude as slight tubercles, and are supported by chitinous borders, which appear 

 circular or elliptical according to the state of contraction of the cutaneous muscles. The 

 diameter of these glands measures about one-third of a millimetre, but in the region about 

 the base of the proboscis and about the anus the diameter is reduced by one-half or even 

 much more. On the proboscis and on the posterior extremity of the body the glands 

 bear villous-like bodies round their opening (HohlpapiUen). These papilte are about 



' Lutends, living in the nmd. 



