134 Proceedings of the Royal Irish Academy. 



little branched. Sometimes, where the surface is thrown by wrinkles into 

 ridges and furrows, the musculature is best developed on the ridges. Sections 

 through the basal part of tentacles show that the musculature is as before on 

 the adoral face, but it gradually thins out and weakens as the great meso- 

 gloeal swelling of the aboral side is reached, and at the back it vanishes 

 altogether. The radial musculature of the oral disc is stronger than the 

 tentacular muscle, but entirely ectodermal. 



iv ' iogy. — The endoderm is deeply pigmented throughout, 



ept as regards the gonads and in part at any rate the ciliated lobes of 



the filaments. The tentacle ectoderm has a fairly narrow, well-marked nerve 



layer, and the usual battery of fairly I i rocysts. It contains pigment 



B aules, but they are far fewer than in the endoderm. The mesenterial 



filament-trefoils have large, well-developed ciliated lobes, with the nuclei 



mcentrated in the inner parts; these, when the larger ciliated 



lobes become folded, form a curious pattern (PL XVI, fig. 28) The glandular 



lobes contain coarsely granular gland-cells which are round, oval, or elongate ; 



and also large, long, nai row shaped, thick walled nematocysts. Ectoderm 



ictinopharynx high and pigmented. Even the mesogloea, in some parts, 



-•■•■in- to ha 1 - anules in its matrix. 



ting shed from other members of the genus by 



erne reduction of the base and enlargement of the oral disc, which 



ilobed and folded double, one half against the other, (b) The 



enterial musculature distinguishes it from A.Plebevut and 



./ ad other details. 



Family SAGARTIIDAE Q 



iniina with well-developed base and basilar muscles. Sphincter meso- 

 ■ d in all. A :itia present. Cinclidespi nt or absent. 



Sub-family SAGARTIINAE Venill. 



- but no cuticle ; 

 sphincter present, mi . than six pairs of perfect mesenteries, 



which thi ' primary mesenteries are fertile except for the 



•lit- S re may or may not be present 



CEREUS Oken. 



// ■ ■■ til Thom ].-■ 



Sagariiinae with the uppei part of the body and the wide oral disc capable 

 ing the lower part; tentacles very numerous, disc sometimes 



