480 Miscellaneous. 



Mediterranean, in which I have found a new form of LitJiocystis. 

 The formation of crystals is not the sole interesting phonomenon 

 which characterizes the evolution of this singular gregarinid. In 

 fact at the moment when the gregarinids, closely attached and 

 almost motionless, begin to encyst, the amoebocytes of the liquid in 

 the cavity of the sea-urchin attach themselves closely to their surface 

 and form a network with dense meshes, each of them putting out a 

 free pseudopodium on the exterior directed normally to the surface 

 of the cyst. All the pseudopodia are rigid and of equal length : 

 this gives to the cyst a bristly appearance, very pecuhar and at first 

 sight very difficult to explain ; but the cause is no longer in doubt 

 when by a very slight compression of the cover-glass a great number 

 of the phagocytes leave the surface of the cyst and form in its 

 neighbourhood an elegant network by the anastomosis of their 

 pseudopodia. 



Afterwards the amoeboid cells are crammed with pigment granules, 

 take on an elongated form, and finally enter into a state of degene- 

 ration, forming blackish masses of plasmodial appearance, which 

 surround the greater number of the cysts. Such is the origin of 

 the supposed plasmodia of LWiocystis, in which an attentive study 

 shows the amoebocytes in all stages : young, very active, with a 

 well-marked nucleus ; others already deformed and filled with 

 pigment, the greater portion completely granular and degenerated. 

 The parasitic product which is known under the name of Litho- 

 cystis is therefore complex. The cysts are those of a monocystic, 

 ccelomic gregarinid of normal evolution, and the crystals are an 

 excretory product ; the coloured plasmodial masses are made up of a 

 collection of the phagocytes of the Echinocardiuni, of which the 

 greater part are dead and charged with granular pigment. By the 

 form of its spores, the Lithocystis falls naturally into the family of 

 the Urosporidae, alongside the genera Urospora and Ceratospora^ of 

 the general cavity of the Siphuuculidfe and the Synaptidae.— C'omjj^es 

 Bendus, 1896, tom. cxxiii. pp. 702-705. (Studies from the Labora- 

 tory at Wimereux.) 



On a Viviparous Ephemera. By M. Causard. 



Viviparity is a condition relatively rare among insects. In fact 

 it is only observed among the Strepsiptera, and exceptionally in the 

 three orders of Hemiptera, Diptera, and Coleoptera. Among the 

 first, many of the AphidaB and the Cochinellidte are viviparous for 

 the parthenogenetic generations. Among the Diptera, the Pupiparae, 

 certain Muscidse {Tachina, Sarcopluvja), and several (Estrids 

 parasitic on mammals : the psedogenesis of the larval forms of Ceci- 

 domyce is also accompanied by viviparity. Lastly, among the 

 Coleoptera there are only known certain Staphylinidae which live 

 as parasites in the ant-hills of South America (/S^»Vrtf7;//m, Corotoca). 



One would certainly not expect to encounter viviparity among 

 the Ephemerae, which have the reputation of living but a very short 

 time in the adult state, a few hours at most, in certain species. 



According to observers, these insects, as soon as born, copulate; 



