t80 NEMERTES CARCINOPHILA. 



merely lying in a " thin albuminous matter" (probably mucus), and covering the bottom of a 

 vessel two inches in diameter. He hazarded the opinion that the mouth was apparently in the 

 anterior part. There is nothing to indicate specific distinction from the present form in the 

 description and figures of the Borlasia camillea of De Quatrefages. I cannot, however, make the 

 same statement with regard to the Emplectonema camillea of Stimpson and the Nemertes camillea 

 of Williams. Two specimens in the British Museum, from Greenland, have very short, thick 

 bodies, and the proboscis in each is proportionally large ; but these appearances may be due in 

 some respects to the mode of preparation. 



This species has sometimes been confounded with " Serpentaria fragilis" (Cerebratulus 

 angulatus). 



3. Nemertes carcinophila, Kolliker. Plate I, fig. 5. 



Specific character. — Eyes two ; proboscis furnished with a central stylet only. Body of a 

 pale pink colour. 



Synonyms. 

 1845. Nemertes carcinophilos, Kolliker. Verhandl. d. Schweiz. naturf. Gesellsch. in Chur., p 89. 

 1850. „ „ Von Siebold. Archiv far Naturges., p. 382. 



1860. Folia involuta, Van Beneden. Keener, sur les Turbell. (sep. copy, from Mem. Acad. Belg., torn. 



xxxii), p. 18, pi. 3. 

 1862. Cephalothrix involuta, Diesing. Revis. der Turbell., p. 254. 



„ Nemertes carcinophila, Ibid. Op. cit., p. 298. 

 1869. Polia involuta (Nemertes carcinophila, Kolliker), Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, 



pt. ii, p. 309 et seq. 



Habitat. — Abounds in tubes attached to the abdominal hairs of female specimens of Carcinus 

 mcenas bearing ova. Messina and the Coast of Belgium. 



Body. — One to two inches long, scarcely so thick as a thread during extension, flat- 

 tened, nearly equal in diameter throughout, or very slightly tapered at head and tail. 



Colour. — Pale skin or slightly pinkish; pale rose-pink in contraction or when coiled 

 en masse. There is a pale patch behind the snout, indicating the region of the proboscis. 



Head. — Slightly tapered towards the anterior end, not defined from the rest of the 

 body, and ending in a blunt snout. Eyes two, situated considerably behind the tip of 

 the latter. 



It is a somewhat sluggish animal, lying doubled in its sheath, or when removed gliding 

 about the vessel in a slow, feeble manner. It is also less hardy in confinement than the majority 

 of the group. 



N. carcinophila spawns in April, and it is easy to watch the development of the young. 



Prof. Kolliker first found the worm in its usual position on a small crab at Messina, and his 

 account of it is quite characteristic. This paper, however, escaped the notice of M. van Beneden, 

 who re-described it as a new species from " Cancer mcenas" many years subsequently. It is not 

 strictly a parasite of the shore-crab, but, like diverse annelids in other sites, it seems to find the 

 hairs of the abdominal feet of females bearing ova a convenient position for its sheaths, and 



