SPONGES 151 



radiate in the body, forms longitudinal fibres in the stalk. Genera 



Stylocordyla, W. Th. (Fig. 38) ; Comdella, O.S. ; Halicometes, Tops. 



Scb-Order 2. tClavulina, Vosm. 



Megascleres monactinal, usually pin-shaped tylostyles, rarely styles. 



Family 1. IClioxidae, Gray. Boring Clavulina. Genera — jCliona, 

 Grant [Cret. Eoc. Mice] ; DofoH«, Crtr. ; tTVioosa, Hanc. [Eoc] ; jAledona, 

 Crtr. [Eoc.]. Family 2. tSpirastrellidae, R. and D. Microscleres, 

 euasters, or streptasters usually accumulated to form an ectosomic crust. 

 Megascleres, tylostyles, or styles ; occasionally diactinal. Genera — Hyme- 

 desmia, Bwk. ; Xenosponyia, Gray; jSjnrastrella, O.S. [Eoc.]; jLatrmi- 

 culia, Boc. [Eoc] ; Sceptrintus, Tops. Family 3. Polymastiidae, Vosm. 

 Without microscleres ; cortex differentiated ; skeletal framework radiate. 

 Genera — Polymastia, Bwk. ; Trichostemma, Sars. ; Rhaphidorus, Tops. ; 

 Proteleia, R. and D. ; Tylexodadus, Tops. ; Sphaerotylus, Tops. ; Quasilina, 

 Norm.; Eidleia, D. ; Tentorium, Vosm. ( = Tlwcaphora, O.S.), (Fig. 31). 

 Family 4. tSuberitidae, Vosm. No microscleres ; no differentiated cor- 

 tex ; framework not radiate ; megascleres nearly always tylostyles. Genera 

 — jSuberites, Ndo. [Eoc] ; Ficulina, Gray ; Laxosuherites, Tops. ; Terpios, 

 Duch. et Mich. ; Pscudosuberites, Tops. ; Prosuherites, Tops. ; Rhizaxinella, 

 Keller ; Semisuberites, Crtr. ; Axosuberites, Tops. ; Poterion, Schlegel. 



Order 2. tHalichondrina, Vosmaer. 



Typically non-corticate ; skeleton usually reticulate ; microscleres 

 monaxon (sigmata chelae, toxa, microrhabdi), very exceptionally polyaxon 

 (euasters in some Axinellidae). 



Family 1. tHaploscleridae, Tops. (= Homorrhaphidae, R. and D. 

 + Heterorrhaphidae, R. and D., pars), Spiculation of a simple tj'pe, 

 very often with diactinal megascleres alone ; microscleres, if present, never 

 chelae. Sub-Family (a). IChalininae, O.S. Skeleton composed of fibres 

 of spongin enveloping diactinal megascleres ; the latter often greatly 

 reduced in size and quantity. Microscleres usually Avanting. Genera — 

 jChalina, Grant [Eoc], (Fig. 34) ; Pachychalina, O.S. ; Siphonochalina, 

 O.S. ; Acervochalina, R. ; Toxochalina, R, ; Chalinida, O.S. ; Sinnosella, 

 Vosm. { = Tuba, Duch. et Mich.); Cacochalina, O.S. ; Sclerochalina, O.S. ; 

 Ceruochalina, Keller. Sub-Family (6). IRenierinae, O.S. Skeleton of 

 spicules sometimes with a confused arrangement, sometimes forming a more 

 or less regular network. Spongin Avanting or jjresent in small quantities, 

 seldom enveloping the spicules completely. Genera — jHalichondria, 

 Flem. [Eoc]; jReniera, Ndo. [Eoc]; Petrosia, Vosm.; Metschnikoxvia, 

 Grimm ; Pellina, O.S. ; Eumastia, O.S. ; Reniochalina, Ldf. ; Gellitis, 

 Gray; Rhaphisia, Tops. ; Menanetia, Tops. ; Astromimus, lAf. ; Damiria, 

 Keller. Sub-Family (c). ISpongillinae, Gray. Fresh water sponges, 

 for the most part similar to Renierinae. Section a. fEuspoXGiLLiNAE 

 ( = SpojIgillixae, Crtr.). The gemmule, so far as it is known, lacks a coat 

 of special spicules. Genera — jSponyilla, Lam. [Jur.], (Fig. 33) ; £ ubomirskia, 

 Dyb. Section /?. Meyexinae, Vejd. The gemmule, when present, has 

 an envelope containing special spicules. Genera — TrochosponyUla, Vejd. ; 



