230 ANATOMY AND PHYSIOLOGY 



FlG. 



9. ATTENUATO-ACUATE. Decreasing gradually in dia- 

 meter from the hemispherical base to the acutely 

 terminated apex. Halichondria infundibuliformis, 

 Johnston. X 160 linear. 



10. FLECTO- ATTENUATO-ACUATE. Attenuato-acute bent 



suddenly near the base of the spiculum. Isodictya 

 infundibuliformis, Bowerbank. X 160 linear. In 

 other species of sponges, and in other forms of 

 spicula, the bending near the base is not so abrupt 

 but it is still characteristic and constant in the 

 species, as for example in the following form : 



11. FLECTO-ACUATE. Halicliondria variantia, Bower- 



bank. X 160 linear. 



12. CYLINDRICAL. Having the shaft of the same diameter 



throughout its length, and terminating at each 

 end hemispherically, as in Pacliymatisma John- 

 stonia, Bowerbank. X 90 linear. 



13. FARCIMULO-CYLINDRICAL. From Spongilla coral- 



loides, Bowerbank. In the Museum of the Royal 

 College of Surgeons. X 108 linear. 



14. NODULATED - CYLINDRICAL VERMICULOID. From 



soundings in the Atlantic 2070 fathoms. X 175 

 linear. 



15. FUSIFORMI-CYLINDRICAL. Having both terminations 



hemispherical, and the shaft gradually increasing 

 in diameter to its middle. Pachymatisma John- 

 stonia, Bowerbank. X 90 linear. 



. DOLIOLATE-CYLINDRICAL. See No. 94, and same 

 number, Plate IV. 



16. FLEXUOUS-CYLINDRICAL. Having the shaft of the 



spiculum curved repeatedly. From Phakellia 

 ventUabrum, Bowerbank. X 160 linear. 



17. ATTENUATO-CYLINDRICAL. Terminating hemispheri- 



cally at both ends, but the shaft slightly decreasing 

 from the base to the apex. Pacliymatisma John- 

 stonia, Bowerbank. X 90 linear. 



