OF THE SPONGlADiB. 347 



Fig. 



113. Trenchant contort BiHAMATE.-^Shewing the cylin- 

 drical form of the shaft at the curves of the hodks, 

 and the middle of the spiculum, and the trenchant 

 edges of th6 remainder of its inner surface. X 

 400 linear. MynikdeM.ia Jokmovd, Bowerbank, 

 MS. From Madeira, Pages 85, 1S7. 



1 1 3. Abbreviated bih amate. — tVom an unknown sponge. 



X 1060 linear. I have foUud but very fi6w speci- 

 mens of this foi'm, and in no cage in sih ; and I 

 am therefore in doubt whether it be an adult 

 spiculum, 01- mutely a variety arising from an 

 arrest of development. 



114. Deflected bihamate. — When the hami are both 



deflected in the same direction at nearly right 

 angles to the plane of the shaft. From Farrea 

 occa, Bowerbank, MS. The sponge is at the base 

 of EvplecteUa cucumer, Owen. X 660 linear. 



115. Exteb-umbonate bihamate. — When the umbo is on 



the middle of the outer curve of the shaft i from an 

 undescribed sponge from Sicily: X 1060 linear. 

 Page 45. 



116. iNTEtt-uMfeoNATE BIHAMATE. — When thfi umbo is on 



the middle of the inner cUrve of the shaft ; from the 

 same sponge as Fig. 115. X 1060 linear. Page 

 45. 



117. Bi-UMBONATE BIHAMATE. — ^Whcu the middle of both 



the inner and outer curve of the shaft have an 

 umbo. From the same sponge as Fig. 115. X 

 1060 linear. Page 45. 



118. Uniclavate BiHAMATBi'^I bcUeve to be an arrest of 



development rather than a separate form; for 

 although I found many specimens of it intermixed 

 with the biclavate forms, I also found others 

 assuming transitional forms, that appeared ulti- 

 mately to connect it with the biclavate spicula. 

 X 1060 linear. Page 44. 



