228 Introduction to Animal Morphology. 



directly under the stomach wall or attached thereto 

 by a funiculus or cord which passes from the stomach 

 to the hinder wall of the body cavity. The ovary is 

 anterior, near the top of the cell, attached to the inner 

 surface of the endocyst, sessile, pillared, or on a special 

 funiculus. The ova and spermatozoa pass into the 

 body cavity, and there probably impregnation takes 

 place. The escape of the sex products thence may be 

 by an opening in the body wall near the anus (Alcy- 

 onella, Farrella, according to Meyer, van Benedeiiy 

 &c.) In Halodactylus gelatinosus, Membranipora 

 pilosa, &c., there is a canal with a ciliated, external 

 mouth, leading from the body cavity outwards, be- 

 tween the base of two tentacles, and joined to them. 

 The embryo, after cleavage, is ciliated and hollow ; 

 soon an opening forms at one end into the hollow, 

 thus forming an intestine ; and a lophophore appears 

 as an eminence on the floor of the cavity. It may in- 

 crease by budding, even before it is perfectly deve- 

 loped. The locomotor embryo is pear-shaped, but 

 soon losing its cilia, it settles down, differentiates into 

 endocyst and ectocyst ; new buds develop from the 

 former, which, growing continuously, build up the 

 colony, each new cell being separated by a partition 

 from its parent. Sometimes stolons are produced 

 from the primary polypide. 



Gemmation is sometimes discontinuous, the separate 

 gemma (statoblasts) springing from the funiculus as flat, 

 ovoid, often spinose, internal buds, consisting of two Avatch- 

 glass-Iike shields, surrounded by a spongy, air-holding 

 annulus ; they are detached when the parent dies, generally 

 in autumn, and grow in the ensuing spring ; they have no 

 blastodermic nor ciliated stage, but many have, according to 

 van Beneden, a structure like a Purkinjean vesicle. In the 



