. Bulletin. Natural history; Natuurlijke historie. 48 MARINE SPONGES. Figure 14. Portion of skeletal framework of Isodictya deichmannae. (Section per- pendicular to surface.) Kent Isl., N. B. YPM :^890. sinoensis, and laxa. These three species intergrade in respect to these characters, and Procter concluded that they are synonymous. E. rigida differs in bearing two categories of styles in respect to width. This same variation occurs in some speci- mens of the East Coast species; these may represent specimens which were pre- served at a time when active spicule-formation was taking place, the t
. Bulletin. Natural history; Natuurlijke historie. 48 MARINE SPONGES. Figure 14. Portion of skeletal framework of Isodictya deichmannae. (Section per- pendicular to surface.) Kent Isl., N. B. YPM :^890. sinoensis, and laxa. These three species intergrade in respect to these characters, and Procter concluded that they are synonymous. E. rigida differs in bearing two categories of styles in respect to width. This same variation occurs in some speci- mens of the East Coast species; these may represent specimens which were pre- served at a time when active spicule-formation was taking place, the thin styles probably representing growth stages. Procter's suggestion that the East and West Coast forms are identical is invalid in the present author's opinion. De Laubenfels' separation of the eastern and western species on the basis of megasclere width seems unjustified unless other characters can be found to differentiate them. More conspicuous characteristics separating the two species are the position and sizes of the oscules. All four of Lambe's species of Esperiopsis bear terminal oscules. Even E. quatsinoensis, which is described and figured with rows of oscules down the sides of the branches, also bears larger oscules at the tips of the branches. Two specimens of this species from St. Lawrence Island, Alaska (AMNH Nos. 264 and 267) were examined by the author. The colonies consist of clusters of branches each of which bears a large terminal oscule. No oscules are present along the side walls of the tubular branches. The oscules are elliptical or circular in outline and vary from 12 mm. x 7 mm. to 3 mm. x 3 mm. in diameter. On the other hand, all of the New England specimens studied by the present author lack terminal oscules and instead have the oscules arranged irregularly or in rows along the sides of the branches. The oscules in these specimens are circular and are much smaller, varying in diameter from 1 mm. to 3 mm. De Laubenfels' species, "deichmannae,"
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