37 



PLATE XV. 



Tethea Collia'Gsh, T'oiverhnnlc. 



Vol. ii, p. 87, 'Mon. Brit. Spungiadfe." 



Fig. 1. — Ptepresents the specimen found by me iu 

 the second of the Guhot caves at Sark, in the condi- 

 tion in which it came fi'om off the rock between hio-h 

 and low- water marks. Natural size. 



There are the basal portions of several small Balani 

 firmly attached to its surface, indicating that it was 

 probably several years old. 



Fig. 2. — A fusiformi-acerate skeleton spiculum. 

 X 80 linear. 



Figs. 3, 4. — Minute, acerate, tension spicula of the 

 dermis. X 80 linear. 



Fig. 6. — A large, attenuato-stellate, retentive spicu- 

 lum from the dermal membrane. X 320 linear. 



Fig. 6. — One of the small, attenuato-stellate, reten- 

 tive spicula of the dermal membrane. X 320 linear. 



Fig. 7. — A fully-developed, geniculated, recurvo- 

 patento, ternate, connecting spiculum. X 80 linear. 



Fig. 8. — The head of one of the geniculated, recurvo- 

 patento, ternate, connecting spicula, not completely 

 developed. X 80 linear. 



Fig. 9. — One of the geniculated, recurvo-patento, 

 ternate, connecting spicula, in an early stage of deve- 

 lopment. X SO linear. 



The immature spicula represented by figs. 8 and 9 

 are very numerous, and every possible intermediate 

 form between figs. 7 and 9 may be observed. 



In vol. i, plate ii, fig. 48, ' Mon. Brit. Spongiadge,' 

 there is a figure of one of the fully developed con- 

 necting spicula of this species as the type of a " genicu- 

 lated, expando-ternate," connecting spiculum. This 



