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NEW YORK STATE MUSEUM 



SPONGE SPICULES 



From camera drawings by the author 



PLATE A 



Ancistroid spicules 

 I A normal and abundant form, doubly hooked at the lower axial 

 extremity, singly knobbed at the upper, the lateral arms represented by a 

 circlet of four up-curved and knobbed rays surrounding the upper terminus 

 of the main axis. 2 A departure from the same structure in the form of 

 the hook which is simple with a pair of lateral outgrowths. 3 A barbed 

 trident. 4. 5 Two-hooked grapnels without evidence of lateral arms. 6 A 

 "cod-hook." 7 Of the type of i. 8 Of the type of 4 and 5. 9 A smooth 

 trident. 10 Trident with long shaft and gracefully recurved hooks. 11 A 

 deeply divided two-hook grapnel with long shaft bearing traces of other 

 arms. 12 Of the type of 2 with more complete development of the primary 

 hook. 13 An anchor with curved shaft and widely divergent hooks. 14 

 Of the type of 2 and 1 2 but with four accessory hooks superposed on the 

 primary hook. 15 A barbed trident as 3. 



