1884.] 85 [Hyatt. 



tents. This fact we also observed and noted in Sp. graminea 

 (Mem. Bost. Soc. Nat. Hist., vol.ii, 1878, p. 506) ; and subsequently- 

 realizing that an actual opening was formed, published a figure in 

 Science Guide, no. 3, p. 26, ed. i, 1879. The projecting cone 

 which marks the site of the opening of the future cloaca has been 

 seen in the larva of Suberites, Tethya, Chalinulaand'Spongia, by 

 Marshall in Reniera, in Verongia by Barrois (op. cit. f. 41), who 

 calls it "la papille anterieure." Carter observed it in Halisarca, 

 and he saw in Halichondria the transformation of the "papilla" 

 into the primitive cloacal crater. (Ann. Mag. Nat. Hist., vol. xiv, 

 pi. 22, p. 335.) 



This appears to sustain Marshall in his conclusion that the prim- 

 itive cloacal canals, as in Ascones, must be considered as normally 

 lined by the endoderm at least in the early stages of Carneo- 

 spongiae. The best discussion of this view, as contrasted with 

 Schultze's opinion that the incurrent canals are formed by an 

 invagination of the ectoderm and that the endoderm is confined to 

 the ampullae and cloacal branches, has been written by Von Len- 

 denfeld in his Monogr. Austral. Sponges (Proc. Linn. Soc. N. S. 

 Wales, vol. ix, pt. 2, p. 313, 318.). The embryology as well as 

 the physiology of the Sponges according to this author appear to 

 favor Marshall's views. Our own view is quite distinct from 

 this, as will be seen farther on. 



Immediately after the larva becomes attached, as shown by 

 Schultze in "Die Plakiniden " (Zeitschr. Wiss. Zool. vol. xxxiv, 

 1880), two hollows are formed in the solid core lined by the endo 

 dermal cells which arise from the core (primitive mesoderm, Mar- 

 shall's coenoblast, and form an epithelial lining around the two 

 separate cavities, which coalesce subsequently into one. Marshall 

 in his article on " Ontogeny of Reniera filigrana " (Zeitsch. Wiss. 

 Zool., vol. xxxvi, 1882), figures the larva as filled up solidly by a 

 " coenoblastic " membrane in which a central cavity appears sur- 

 rounded by the cells of an endoderm and a mesoderm both differ- 

 entiated from the " coenoblast." This name appears to us to em- 

 body an essential distinction which ought to be made between the 

 primitive layer and the endoderm and mesoderm which arise from 

 it, if Marshall's view is true. The colored cells in the interior 

 of Esperia Lorenzii and the arising of the endoderm from inva- 

 larva gination in Calcispongiae and probably also in Carneospon- 



