NOTES AND MEMORANDA. 285 



that the two systems communicate and only form one single 

 apparatus. 



The fine peripheral vessels communicate by very fine and very 

 short vessels with the calcareous corpuscles scattered over the surface 

 of the body. 



The apparatus must therefore be an excretory apparatus. It 

 might perhaps also serve as an organ of absorption and nutrition, the 

 fine peripheral vessels conducting the absorbed products into the large 

 vessels, which would distribute them into the deeper parts of the 

 organism. 



Anatomy and Embryogeny of the Taeniadse. — A preliminary 

 communication on this subject by M. Monier * is chiefly a revision or 

 criticism of the results of Sommer on T. mediocanellata and T. solium ; 

 the author justly observes that the excellent work of the German 

 helminthologist seemed to be one which would be for a long time 

 accepted as classical. The mother-cells of the spermatozoids are 

 formed in the midst of a mass of central tissue, and there are no 

 proper seminal ducts through which they may escape; this explains 

 why they are provided with that long and aj^parently useless flagel- 

 lum. What seminal tubes there are, are formed by a kind of excretion 

 around the bundles of spermatozoids, and do not ordinarily become 

 easily visible, except when, as in T. cerebralis, they are pigmented. 

 In some species there appear to be two sets of spermatozoids, which 

 become mature at different periods. The uterus does not receive the 

 ova, which are formed in just the same place and in just the same way 

 as the spermatozoids. 



The Hauptdoiter and Nehendotter of Sommer are stated to be merely 

 extended ectodermal masses, one of which — the former — sometimes 

 forms a kind of envelope for the egg. The so-called circular muscular 

 layer is, in the young, found to give off fibres to the interior and to 

 the exterior ; these fibres are separated perij)herally and unite at their 

 centre to form the " parenchyma " ; where they join the cuticle they 

 form a very dense layer. Further observations are promised. 



Parasites of the LamellibrancMata. — TJlicnyf gives an account 

 of some observations on these parasites. 



In Cyclas rivicola he finds a form of which little seems to be known, 

 although it appears to be the Cercaria Cjjdadis rivicolce of Diesing. 

 These forms, which were found in sporocysts, imbedded in the 

 generative organs of their host, were, thanks to their tail, capable of 

 a large amount of movement ; they are provided with a terminal 

 oval sucker, above which there is a spine ; in the anterior part of 

 the last third of the body is placed the ventral sucker, which is as 

 broad as the body. The most interesting region is the terminal or 

 caudal portion. Connected by a narrow stalk with the end of the 

 body there is a pyriform bulb, the surface of which is thrown into 

 a number of folds ; the interior of this enlargement is filled with a 

 thick fluid, in which small vacuoles may be frec[uently observed, and 



* ' Rev. Internat. des Sci.,' ii. (1878) 689. 



t ' Arch, fur Naturgeschichte,' xliv. (1878) 211. 



