198 Miscellaneous. 



the worm suddenly into absolute alcohol, or to make it die slowly in 

 the water by gradually substituting fresh water for the sea-water in 

 which it is immersed. We frequently find individuals which have 

 regenerated a more or less considerable portion of their body. 

 When placed in a liquid which does not suit it, the worm pushes 

 out its trunk and throws it oft". The trunk, thus isolated, still con- 

 tinues to live for a long time ; it invaginates and evaginates itself, 

 and moves with a tolerably rapid creeping motion. One might 

 suppose that we had here a case of viviparity. 



The organization of our Nemertean is precisely that of the 

 unarmed Nemerteans or Anopla ; but the generic characters do not 

 agree with those of any type previously described. The head, which 

 is clearly distinct from the body, has the form of a heart with the 

 point directed forward, and presents an aperture for the protrusion 

 of the trunk. The sides of this head are occupied, throughout their 

 whole length, by two enormous longitudinal cephalic fissures. The 

 upper part is strongly pigmented, but there is no apparatus of 

 vision, which may easil)' be explained by the subterranean existence 

 of the animal. The mouth occupies the anterior and ventral part 

 of the trunk ; it is about 1 ceutim. in length, and consequently 

 quite visible to the naked eye. The anterior part of the body, for a 

 length of about a decimetre, is occupied by a straight oesophagus 

 situated beneath the cavity of the trunk. Following this oesophagus 

 the digestive tube proper |commences. This point is marked by a 

 change in the musculature. Here begins a ventral furrow, which 

 traverses the whole body of the animal to the anus. 



The cseca of the intestine are not placed opposite to each other 

 two and two ; on the contrary, there is a very marked alternation 

 in the points of insertion of these organs to the right and left 

 of the digestive tube. The cajca are not simple ; they branch at 

 their extremities into secondary diverticula, in such a manner that 

 the intestine presents a true dendroccelism. Such an arrangement 

 as this had only been indicated previously in a pelagic Nemertean, 

 the curious Pelagonemertes RoUestotii, two specimens of which were 

 collected and studied by Moseley during the ' Challenger' expedition. 



The lateral vessels do not appear to be so well organized as the 

 dorsal trunk; they are rather lacunar, comparable with those which 

 occTipy the same position in the Cestodea. Perhaps they may stand 

 in relation to the genital organs, which alternate with the cseca of 

 the digestive tube.; I have not met with specimens young enough 

 to decide this question. 



The genital pores do not open upon the sides of the body, as 

 is the general rule in the Nemerteans, but upon the dorsal 

 surface and on each side of the median dorsal line. They are dis- 

 seminated in an alternate and slightly irregular fashion, nearly like 

 the pores of the ambulacral plates of certain sea-urchins. The 

 spermatozoids are perfectly filiform, and very long. The ova 

 are exceedingly small, and are laid separately, each surrounded 

 by a thick mucous envelope. The nutritive vitellus is scanty. 

 Therefore, although I have not been able to follow the development, 

 I am convinced that the cmbryogcny must be dilated and that the 

 larva must aft'cct the Pilidium-iorm. 



