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



of the numerous reproductive receptacles. These are not situated alternately between 

 each pair of intestinal caeca right and left, as we find in the majority both of Hoplo- 

 nemertea and Schizonemertea. In Amphiporus moseleyi, the distribution of the genital 

 receptacles appears to follow a more primitive arrangement, and offers many points of 

 similarity with what obtains in the Palseonemertean Carinella, where there is not yet a 

 regular metamerical arrangement of the genital sacs, but where there are short independent 

 cavities, irregularly distributed under the dorsal body- wall, which they pierce by means 

 of short ducts. The outer openings of these ducts are seen on the dark dorsal surface of 

 the animal as so many fine white dots irregularly spread between the transverse and longi- 

 tudinal white lines that form such well-defined external markings in the species in cpiestion. 



Amphiporus moseleyi, as will be seen on comparison of figs. 4 and 7 of PL IX., has its 

 generative sacs distributed very much in the same way, with this difference, however, 

 that generative pores are situated not only on the dorsal but also on the ventral surface 

 of the animal. When the animal is very ripe and the generative sacs are overfilled, it is 

 manifest that this specific character may be more easily detected in every transverse 

 section than in young or unripe specimens. As many as seven separate sacs in one 

 section were noticed. Both the male and female sex were found to agree in this respect. 



Another character peculiar to nearly all Amphipori — the coalescence of the oral and 

 the proboscidian aperture into a common wider opening, situated just below the tip of 

 the snout — is also met with in Amphiporus moseleyi. 



Amphiporus marioni, n. sp. (PI. IX. fig. 3; PI. X. fig. 1; PI. XV. figs. 14, 15). 



A second species of Amphiporus is represented in the Challenger collections by two 

 specimens, the larger coming from Marion Island, and having been collected on December 

 26, 1873 ; the other from Christmas Harbour, Kerguelen, at a depth of 120 fathoms. 



The place at which the first specimen was obtained was an inducement to dedicate 

 this species, in preference to any other of the novelties of the Challenger, to the indefatig- 

 able naturalist of Marsedles, so well known by his numerous researches in the field of 

 invertebrate morphology. 



Amphiporus marioni, was one of the larger sized specimens, measuring 5^ mm. in 

 diameter anteriorly in its widest region. The body musculature may be said to be 

 stronger than in most of the other Hoplonemertea (cf. PL IX. figs. 1-6) ; the longi- 

 tudinal muscular layer shows a very marked pennate arrangement of the bundles (PL X. 

 fig. 1) between which the gelatinous tissue penetrates, carrying with it massive nerve- 

 stems which assume a more or less flattened, plexus-like arrangement, just between this 

 longitudinal layer a and the circular layer /3 (PL X. fig. 1, ne). The proboscidian sheath 

 is also very muscular ; the proboscis has the stylet of the normal Amphiporean shape. 



The nephridial system is comparatively short and has one pair of deferent ducts 



