412 



Nemertes carcinophila Me Intosh. 



British Annelids: Part I. Nemerteans, Ray Society, London, 



1873. 

 Host: Carcinus maenas^ egg-masses; St. Andrews, Scotland. 

 ? Cephalothrix galatJieae Dieck. 



Jenaische Zeitschr. f. Naturwiss. Bd. VIII. p. 500 — 520; 



Taf. XX, XXI. 1874. 

 Host: Galathea strigosa] gills when young, egg-masses when 

 mature; Messina. 

 ? Polia xanthophila Giard. 



Bull. Sc. de la France et de la Belgique, Tome XX. p. 496, 



1888. 

 Host: Egg-masses of Xantho floridus ^ Northern coast of 

 France. 

 Eunemertes carcinophila Joubin. 



Les Némertiens, Faune Française, Paris, 1893. 

 Host: Carcinus maenas^ Northern coast of France. 

 Eunemertes carcinophila Burger. 



Nemertinen, Fauna und Flora des Golfes von Neapel, Monogr. 

 XXII. 1895. 

 Body slender, commonly 6 — 15 mm long when found on gills, 

 20 — 70 mm long when sexually mature; color yellowish, orange, pale 

 reddish, rose-pink (Mcintosh), or bright brick-red; posterior pro- 

 boscis chamber very small, rounded; in ordinary states of contraction 

 central stylet lies immediately behind the brain. Basis of central 

 stylet slender, about 0,25 — 0,3 mm in length by 0,06 — 0,08 mm in 

 average diameter. Central stylet about 0,08 — 0,12 mm long, or be- 

 tween one-third and oue-half as basis. 



Parasitic on the gills of various species of crabs when young, mi- 

 grating to the egg- masses of the crab when sexually mature. 



As was pointed out in the American Naturalist for March, 1902, 

 Dieck' s species agrees perfectly with Koelliker'siV. carcinophilos in 

 such a large number of details that there is strong evidence that the 

 two forms are specifically identical, or at any rate very closely related 

 — that they can belong to different orders seems incredible. 



The only differences which are mentioned for Giard' s Polia xan- 

 thophila is its smaller size and different host. 



Many observations indicate that the worms spend their whole 

 existence on the crab, for they have been found under no other con- 

 ditions, and those found on the crab are met with in all stages of deve- 

 lopment. On the New England coast their life-history is briefly as fol- 

 lows: Eggs laid in mucous tubes among the egg-masses of the crab in 



