ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 33 



follicular capsule ; this follicle has a solid stalk, which leads into the 

 oviduct ; where the wall of the respiratory cavity is connected with 

 this, it is thickened, and the projection so formed was taken by 

 Todaro for the uterus ; the maturation of the ovum is always 

 accompanied by the shortening of the stalk, till the follicular cavity 

 becomes connected with the oviduct. After this impregnation takes 

 place. 



In further development differences obtain between the species as 

 to the form of the embryo, of its coverings, and of the number of 

 follicular cells. Considerable differences are seen early between 

 S. democratica and S. bicaudata ; the former has no amniotic fold, the 

 latter lies in a prolongation of the body, formed from the cellulose- 

 mantle, blood sinuses, and a tubular continuation of the wall of the 

 respiratory cavity. The first signs of the differentiation of the 

 central mass is the separation of the lower wall of the follicle, and a 

 cavity is thus formed which the author proposes to call the follicular 

 cavity, instead of applying Todaro's unsuitable term of cleavage- 

 cavity ; this wall becomes the upper wall of the placenta. In 

 ;S^. pinnata the nervous system arises in the form of a tube with an 

 at first narrow lumen. In the other species the ganglion has the 

 form of an aggregate of cells, derived from the follicular cells. 

 From the connecting canal between the enteric and neural cavities 

 we have formed a ciliated pit. An account is given of the 

 formation of a special organ known as the subpericardial aggregate 

 of cells ; Uljanin has informed the author that a similar structure is 

 to be observed in Doliolum. The el^eoblast is formed from the 

 amoeboid follicular cells which give rise to the blood-corpuscles and 

 muscles. 



The author insists on the great differences between the develop- 

 mental history of Salpce and that of other animals, the organs being 

 formed not from the cleavage, but from the follicular cells ; some- 

 thing similar has, however, been noted in the allied Pyrosoma ; and, 

 instead of speaking of development of Salpce, he would prefer to give 

 the process the name of follicular gemmation. 



Tunicata of the ' Challenger.' * — In a fourth communication 

 Dr. W. A. Herdmann deals with the Molgulidae, and describes 

 Molgula pedunculata, horrida, forhesi, and pyriformis, Eugyra kergue- 

 lenensis ; Ascopera is a new genus with a pyriform, more or less 

 pedunculated body, the test thin, while the branchial sac has seven 

 folds on either side : A. gigantea and A. pedunculata. 



Arthropoda. 

 a. Insecta. 



Striated Muscle of Coleoptera and its Nerve-endings.f — The 

 main results obtained by Professor L. v. Thanhofter on this subject 

 show the striated muscle of Coleoptera to possess two separate sarco- 

 lemmar membranes, between which the nerve-ending plate spreads 



* Proc. Boy. Soc. Edinb., 1881, pp. 233-40. 

 t Biolog. Centralblatt, i. (1881) pp. 349-51. 



Ser. 2.— Vol. II. D 



