304 Miscellaneous. 



cysts remain in the gizzard for a longer or shorter time, and then 

 pass into the duodenum, where they undergo the action of the 

 digestive juices. Their envelope is soon dissolved, and the young 

 Distomum set at liberty. It then slowly traverses the numerous 

 folds of the small intestine ; but during this course its genital organs 

 are developed, and when it arrives in the rectum its ova are mature, 

 fecundated, and ready to be eliminated. 



It remained to learn in what invertebrate animals the Cercariae 

 encysted themselves. I can tell this now, thanks to the method 

 above indicated. The Cercariae of D. bmchysomum are encysted in 

 small Isopod crustaceans belonging to the genus Anthura, and to a 

 species very common on the shores of the English Channel — namely, 

 Anthura gracilis, Leach. The Cercariae of D. Jcptosomum become 

 encysted on the siphons and in the foot of a small Acephalous mol- 

 lusk, which lives at a small distance from the shore — Scrobicularia 

 tenuis. This mollusk and crustacean, with a few larvae of Diptera, 

 constitute the ordinary nourishment of Tringa alpina. 



I have also observed other encysted Cercariae which are parasitic 

 on Crustaceans, but of the subsequent development of which I am 

 ignorant. One occurs in Mysis, and is distinguished by the larger 

 size of its two suckers. The other inhabits the visceral cavity of 

 Ligia oceanica, and is remarkable for its large dimensions : its cyst 

 is 0*280 millim. in diameter and 0-032 millim. in thickness. 



Scrobicularia tenuis has furnished me with three species of sporo- 

 cysts, which perhaps belong to the Distoma of which I have spoken. 

 The Cercariae which issue from them are very fine. Two of them 

 appear allied to O. dichotoma and C. setifera, found in the free state 

 in the Mediterranean by J. Midler. The third is certainly new, and 

 is characterized by its tail, which is furnished with very short setae 

 arranged in rings. 



I may also mention, in conclusion, three remarkable types of which 

 I only know the adult form : — a Monostomum with a winged head 

 and large sucker, which lives in the intestine of Strepsilas interpres ; 

 a Holostomum with scaly integuments, parasitic in the same bird ; 

 and a gigantic Distomum, a parasite of Echinorhinus spinosus, which 

 was described by Risso under the name of D. scimna, and which I 

 have just detected at Roscoff in the same Selachian. The large size 

 of this last species, and the consistency of its organs, particularly 

 fit it for histological investigations ; I shall give its detailed anatomy 

 in a memoir that I am now preparing. — Comptes Bendus, September 13, 

 1875, p. 475. 



Bathybius. 



According to some observations of Prof. Wyville Thomson, com- 

 municated by Prof. Huxley to ' Nature ' (August 19, 1875), 

 Bathybius probably consists of sulphate of lime precipitated in a 

 flocculent state by strong alcohol. 



