20 THE V^OYAGE OF H.M.S. CHALLENGEE. 



round the opoiiino- of each gknd. These structures do not, however, form papillte, Ijut at 

 most appear as flat tubercles when the body-wall is very powerfully contracted. 



The whole proboscis is thickly studded with hooks of two forms. On the anterior 

 half the hooks are flattened, with a strongly curved double point; they measure 

 0-032 mm. in height, and are arranged in distinct rings. On the posterior half of the 

 proboscis the hooks are scattered and in the form of three-sided pyramids, with but 

 sliohtly l)ent points. Over the whole proboscis are seen the openings of the ducts 

 (0-017 mm. in length) of the cutaneous glands. On the anterior half of the proboscis 

 these occur in rows between the rings of hooks, about one duct for every three to five 

 hooks ; on the posterior half of the proboscis they occur much more sparingly, and are 

 scattered. 



The anal and caudal shields are formed from numerous small polygonal or rounded 

 chitinous plates, which are somewhat larger and thicker round the margins of the shields. 



The intestine forms a spiral, and a small diverticulum is present. There are two very 

 larse seemental organs, which are for half their length attached by means of mesenteries. 



St. Vincent (Cape Verde Islands) ; shallow water. 



20. Aspidosiphon triincatus, Keferstein. 



AspidosipJwn trunmfus, Keferstein, LTntersuclumg iiber eiuige amerikanischc Sipunculiden, 



Zeitschr. f. wiss. Zool.,^1866, xvii. p. 50, Taf. vi. figs. 15-18. 

 Asp!dosipJw7i tnmcafiis, Selenka and Bulow, Die Sipuncnliden, &c. {loc. cit.), pp. 118, 119, 



Taf. xiii. figs. 193-195. 



The body is brown, the two grooved shields are of a darker colour. The grooves of 

 the anal shield run from the ventral side to the margin, those of the caudal shield run in 

 radiate fashion. There are numerous rings of very small bent hooks. The longitudinal 

 musculature is divided into strands. The retractor of the proboscis has two roots which 

 originate on the posterior shield. At the point where the intestinal spiral passes into the 

 rectum there is a diverticulum in connection with the latter. Both segmental organs are 

 for the most part attached by mesentery to the body-wall. 



Of this species a large number of specimens from the Philippines have been preserved, 

 and I find after examination that they do not in any way difi"er from those forms which 

 Agassiz found ofi' Panama, and ]\Iobius ofi" Mauritius. The range of distribution must 

 therefore be very wide. It might indeed be possible on close comparison to establish 

 between our forms and those investigated by Keferstein a difference great enough to be 

 considered a specific distinction, but with the form from Mauritius the Philippine species 

 is certainly identical. 



The animals were on an average 17 mm. long, not including the proboscis. 



Habitat.— ^t&tion 201, October 26, 1874 ; lat. 7° 3' N., long. 121° 48' E. ; depth, 82 

 fathoms ; stones and gravel ; trawled. 



