SPONQIDA. 
4 Spon^. 
Ilircinia, Nardo, (Filifera, &c.). The “ Spongiophaga ” of Carter is 
probably parasitic. H. campana, N., H. arhusculum, sp. n. {vide infra) 
II. acuta^ H3^, II. cartilaginea^ Hy., II. purpurea^ Hy. 
Fam. 4. Ceratellidce^ Gray, 
Gen. Ceratella, Gray, and Dihitella, Gray, are undoubtedly the same 
genus. C. labyrinthica, sp. n. (vide infra). 
Hyatt considers the fistular adult forms of the Spongiidce as homo- 
logous with a number of the embryonic cloacae which have become 
laterally fused (cf. Hackel). He gives a careful account of the varieties, 
and relations to depth and temperature, of the species above-uamed. 
Development (vide in/rd). Many of the species are figured. 
Tuba perhaps belongs to the Spongiince. 
Ilaliphysema (W). Apparently a Sponge; the simplest form of the 
group, each individual representing a “ ciliated chamber.” 
Order Holoruhapiiidota (Carter). 
Sollas (19) gives the results of his experiments on the spicules of the 
following : — 
Halichondria incrustans and H. panicea. 
Trachya sp., Pachymatisma johnstonia, Geodia arabica, and of some 
Hexactinellids, which give interesting and suggestive facts as to the 
development and typical structure, and as to the changes wrought in 
fossil forms and recent spicules, at the sea-bottom. 
Thecophora ibla, W. Th., (18) taken in 60-G0 fathoms, on St. George’s 
Banks, North America (cf. p. 55, & pi. vii. fig. 1). 
Spongilla fluviatilis, Johnst., (5) p. 45. The smooth acerate spicules 
develope from centrally inflated forms. 
Wyvillethomso7iia, Wright, (14) referred to Stelletta. 
Viscodei'mia polydiscus, Boo. Figured in Sollas’s paper on Siphonia 
(cf . fossil forms, infra) . 
Order Hexactinellida. 
Zittel (22) revises the whole of the recent and fossil genera. He states 
his belief of the entire distinctness of the group from the Lithistids and 
all others, and puts forward the following classification of the group, 
based mainly on microscopic characters : — 
Suborder AyssaAjina [-ac-], Zittel. Forms in which the skeleton-spi- 
cules generally remain united by sarcode only (= Sarcohexactinellidce, 
Carter, with Euplectella aspergillum and E. cucumer). 
Suborder Dictyonina, Zittel. Forms with the skeleton-spicules regularly 
coalescent into latticework with angular meshes. He regards the form 
of the crossing-nodes as an important classificatory point. 
Minor divisions: — I. Dictyonina. Fam. 1. Astylospongidce. Un- 
stalked body, very thick walled ; system of canals radiating from 
centre to surface ; framework irregular ; nodes solid. 
(Genera, Astylospongia,'R6m., Palceomanon, Bom., Protachilleum, Zitt., 
Eospnngia, Billings ; diagnoses given ) 
Fam. 2. Euretidce. Cup-shaped; skeleton latticed; nodes imperforate : 
surface fundamentally naked. • 
(Genera, ? Pi'otospongia, Salter, Calathium, Billings, A^'clicjeocyathus, 
Billings, ? Trachyum,'B\\\mg'&,? Steganodicty on, M.qGoy, Tremadictyon, g.n. 
