EMBRYOLOGY. 33 



restraining membrane of the ovary, and escape into the cavity of the endocyst. Attached by 

 one extremity to the external surface of the stomach, near the commencement of the intestine, 

 and by the other attached to the walls of the cell, and apparently also in connection at this 

 place vt'ith the ovary, is a cylindrical flexible chord (anterior funiculus) (PI. X, figs. 3, 4, 6'), 

 which obeys all the motions of the stomach. It exactly resembles that already described as 

 attached to the fundus of the stomach and bottom of the cell in Alcyonella. 



The testicle in Paludicella is an irregularly lobed mass (PI. X, figs. 3, 4, yr), attached, like 

 the ovary, to the inner surface of the endocyst. It is situated near the bottom of the cell, 

 and is thus, as in Alcyonella, separated, by a considerable interval, from the ovary; it is 

 connected with the stomach by a cylindrical chord, or posterior funiculus (PI. X, figs. 3, 4, 0), 

 similar in all respects to t\\e funiculus of Alcyonella, and, except in position, to the anterior 

 funiculus of the present genus. The testicle was coexistent with the ovary, and was loaded 

 with spermatozoa, multitudes of which projected from its surface, presenting quite the same 

 appearance as in Alcyonella, while many had escaped from the testicle, and were observed to 

 be carried along in the currents of the perigastric fluid, or might be seen clustering round 

 the ovary. The testicle is here, as in Alcyonella, composed of mother-cells (PI. XI, fig. 24), 

 containing distinctly nucleated vesicles of evolution. The spermatozoa are formed by the 

 transformation of the nucleus. They have a terminal enlargement of an elongated piriform 

 shape (PI. XI, fig. 25), and exhibit a constant sinuous or undulatory motion. 



(2.) Embryology and Gemmation. 



Development of the Ovum. — I have succeeded in tracing the development of the ovum 

 through most of its stages in Alcyonella funyosa. 



In this polyzoon the mature ovum consists of a granular vitellus, surrounded by a very 

 evident vitellary membrane, on whose internal surface the contents appear frequently to be 

 aggregated in a coarser granular layer (PI. XI, figs. 26, 27). It presents a large germinal 

 vesicle, and a very distinct germinal spot. After a time the germinal vesicle and germinal 

 spot disappear, and the vitellus undergoes segmentation, and after the mulberry-like condition 

 thus induced has in its turn vanished, we find that the contents of the egg have assumed the 

 form of a roundish or oval body (PI. XI, fig. 29), richly ciliated on its surface, and provided 

 with a large central cavity, which as yet does not open externally. When liberated from the 

 outer membrane of the ovum, which still confines it, it swims actively through the surrounding 

 water by the aid of the cilia with which it is invested. 



As development proceeds, we find the ciliated embryo, while still confined within the 

 coverings of the egg, presenting in some part of its surface an opening which leads into the 

 central cavity ; and through this opening an unciliated, hernia-like sac is capable of being- 

 protruded by a process of evagination. The unciliated protrusible portion would seem to 

 have been derived by a separation from the walls of the central cavity, and appears 

 therefore to originate by a process of unlinin j, a true chorization. 



5 



