ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 171 



The epithelial sac is first formed by a live Trematode, which may or 

 may not persist there. The observations of Filippi, Mobius, and others 

 are here confirmed. Sporozoa may also cause sacs. 



The parasite of the mussel occurs in sporocyst stage in Tapes decus- 

 satus and Cardium edide ; from these bivalves the cercarias migrate to 

 the mussel, as has been proved experimentally. It is almost certain that 

 the adult stage of the parasite is Distomum (Lcucithodendriuui) somaterioz 

 Lev., found in the intestine of eider-duck and scoter. 



The author suggests that artificial infection of pearl-oysters or pearl- 

 mussels might turn out very profitable, and points out the futility of 

 transferring young pearl-oysters to more convenient ground near shore 

 unless it is certain that they are infected or will be infected. Perhaps, 

 the popular estimation of pearls will not be enhanced by these discoveries 

 which proclaim them to be the cenotaphs of flukes. 



Muscular Apparatus of Anomia.* — Jobert describes the structure 

 of the adductor and ossicular muscle in Anomia ephippium, which opens, 

 and shuts its shell at almost regular intervals. The adductor includes 

 striped and smooth muscle-fibres and a white band of fibrillar elastic 

 tissue. The ossicular muscle of the adults is digastric, and the same 

 three kinds of tissue are seen to be arranged in a very characteristic 

 fashion. The brusque closure is due to the striped fibres ; the elastic 

 tissue and the smooth fibres effect slow closing 'and permanent closure. 

 Jobert notes the close resemblance between the musculature of Anomia 

 and that of Pecten. 



Synopsis of Carditacea. j — W. H. Dall adds to his previous synopses, 

 one dealing with the Carditacea, a group intimately related to the 

 CrassatellitidEe, Astartidre, and Chamidae. He directs attention, inter 

 alia, to the absence of siphons, to the coarsely reticular gills, to the 

 incubation within the atrium of the ovary or a specially developed fold 

 of the ventral part of the mantle lobes which secretes and lines a shelly 

 marsupium, to the sedentary life and usual occurrence of byssus in youth, 

 at least, to the mutable features of the hinge, and so on. The Carditacea. 

 are divided into the Carditidas with the ligament and resilium external 

 and united, and Condylocardiidas, with the resilium immersed and the 

 hinge in a more or less permanently and imperfect state. Dall's synopsis, 

 includes seven new species. 



Arthropoda. 

 a. Insecta. 



Sensitiveness of Ants to Ultra-Violet and Rbntgen Rays.J — 

 A. Forel and H. Dufour describe experiments which seem to remove 

 all doubt from the conclusion that ants (Formica fusca) react to ultra- 

 violet rays. The results of the experiments agree with those previously 

 reached by Lubbock, Graber, and Forel. Under the influence of X-rays 

 the ants remained motionless and were apparently quite unaffected. 



* Comptes Kendus, cxxxv. (1902) pp. 906-7. 



t Proc. Acad. Nat. Sei. Philadelphia, 1902, pp. 696-716. 



X Zool. Jahrb., xvii. (1902) pp. 335-8. 



