SPONGIABIA 79 



Order 2. MONACTINELLIDA. 



Sponges ill which the skeleton consists of needle-like (monaxonic) 

 spicules and sometimes other kinds, with or without spongin fibres: 20 

 families, grouped in 2 suborders, and numerous species, constituting the 

 majority of all sxionges; mostly in shallow water j 1 family in fresh 

 water. 



Key to the suborders of MonactineUida: 



Qi Sponge compact, usually massive 1. HADROif:ERiNA 



O2 Sponge not compact, usually with spongin 2. Halichondeina 



Suborder 1. HADROMERINA. 



Body compact, having a hard outside crust or cortex, and usually 

 massive but sometimes cup-shaped or stalked; spongin absent or very 

 poorly developed: 8 families. 



Family 1. TETHYIDAE. 



Body spherical, with sli'ght projections on the surface caused by the 

 protrusion of the end of bundles of long needles (inegascleres) without 

 heads which extend radially from the centre of the body; no spongin 

 fibres present: 6 genera. 



Tethya Lamarck. Body with a thick, leathery rind and the form 

 and color of a small orange : several species. 



T. hispida Bowerbank. In 8 to 35 fathoms in Casco Bay, Maine. 



Family 2. SUBERITIDAE. 



Form massive; substance compact and firm; spicules (megascleres) 

 are needles with heads; without microscleres or spongin: 15 genera. 



SuBERiTES Nardo. Form various, often massive, sometimes pedun- 

 culate ; outer surface smooth : 15 species. 



S. compacta Verrill. Body irregular, being an elongated mass 

 attached by one edge ; length up to 15 cm. ; width and height 2 to 8 cm. ; 

 color bright yellow; surface smooth; oscula inconspicuous: Maine to 

 Virginia in shallow water; often on the shells of hermit crabs. 



Family 3. POLYMASTIIDAE. 



Form massive, often spherical, with long needles extending radially 

 from the centre; with the surface covered with small protuberances, 

 some of which have an osculum; no microscleres or spongin: 13 genera. 



Polymastia Bowerbank. Smaller needle and pin-shaped spicules 

 in addition to the radial ones present. 



P. robusta Bow. Form irregular; color yellow or gray; diameter 



