532 DR. J. E. GRAY ON SPONGES. [May 9, 



When the two ends are equally developed they are equianchorate, 

 when unequal ineqvianchoi'ate, and the ends are distinguished as 

 bidentate, tridentate, and palmate. 



Simple forms of spicula have the same shape from the beginning 

 to the termination of their growth. 



Synopsis of sections of family. 



I. Defensive spicules unilateral, inequianchorate, attached to the 

 skeleton. 



* Flukes entire, with central ridge (Genera nos. 1—4). 

 ** Flukes palmate (Genus no. 5). 



II. Defensive spicules unilateral, bi- or tripolicated, free in the 

 sarcode (Genera nos. 6 & 7). 



III. Defensive spicules unilateral, equianchorate, free in the sarcode. 



* Flukes divided into two or three spines at each end (Genera 



nos. 8-19). 

 ** Flukes oblong, concave, with a central apical tubercle (Genus 

 no. 20). 

 *** Flukes cup-shaped, acute at each side (Genus no. 21). 

 **** Spicules boat-shaped, with marginal sides (Genus no. 22). 



IV. Defensive spicules compressed, bihamate, hooked at each end 



(Genus no. 23). 



V. Defensive spicules bihamate or contorted only (Genera nos. 

 24-30). 



VI. Defensive spicules regular, with rotate rays at each end (Genus 

 no. 31). 



I. Defensive spicules unilateral, inequianchorate, attached to the 



skeleton. 



* Flukes entire, with a single central ridge, with a spine at its base. 



1. EsPERiA, Nardo (part.), O. Schmidt, p. 54. 



Sponge branched, flexible, netted. Spicules of three kinds, united 

 in the horny matter: — 1. Pin-shaped. 2. Bihamate — that is, slen- 

 der, cylindrical, bent up at each end, regular or tortose. 3. Equi- 

 anchorate, minute ; flukes ovate, with a central ridge ending in a 

 spine below. 



EsPERiA TYPicA, Nardo. 



Esperia contavenii, O. Schmidt, p. 54, t. 5. f. 2 (pin-shaped spi- 

 cules, double-headed, with a subbasal cross bar). B.M. 

 Hab. Adriatic. 



