8i)onge-fauna of Norway. 161 



2. T. arahica, Carter, A. & M. N. H. 1869, vol iv. p. 3, 

 p. i. figs. 1 to 13, pi. ii. figs. 19 and 20. Lac. S.E. Arabia. 



3. T. atrojmqmroidea, Carter, A. & M. N. H. 1870, vol. vi, 

 p. 176, pi. xiii. figs. 1-10. Loc. Unknown, Distinguished 

 by its large liamates, which are spined, three terminal spines 

 at each end giving them a resemblance to a tridentate an- 

 chorate. 



4. T. casula, Carter, A. & M. N. H. 1871, vol. viii. ]). 99, 

 pi. iv. figs. 1-9. Loc. Port Elizabeth, Natal, Cape of Good 

 Hope. Distinguished by absence of grapnel-like anchors and 

 general form. 



5. T. dactyloidea^ Carter, A. & M. N. H. 1869, vol. iii. 

 p. 15; 1872, vol. ix. p. 82, pi. x. figs. 1-5. Loc. S.E. coast 

 of Arabia. 



6. T. ewploccmms^ O. S. Spong. Algier. 1868, p. 40, pi. v. 

 fig. 10. Desterro, Brazil. 



7. T. inskUosa, O. S. Atl. Spong. Faun. 1870^ ji. 60, pi. vi. 

 fig. 11. Loc. Florida, 17 fms. 



8. T. lens, O. S. Atl. Spono-. Faun. 1870, p. 66, pi. vl. 

 fig. 10. Loc. Florida, 135-152 fms. 



9. T.polyura, O. S. Atl. Spong. Faun. 1870, p. 66, pi. vi. 

 fig. 8. Iceland, 85 fms. 



10. T. radiata, Selenka, Zeit. f. wiss. Zool. 1880, xxxiii. 

 p. 467, pi. xxvii. Loc. Bay of Rio Janeiro, 3 fms. 



11. T. smiillima, Bwk. Proc. Zool. Soc. 1873, p. 15, pi. iii. 

 figs. 6-13. Loc. South Seas. 



12. T. tethyoides, O. S. Atl. Spong. Faun. 1870, p. 66, 

 pi. vi. fig. 9. Loc. Florida, 100-123 fms. ; Iceland. 



13. T. zetlandica. Carter, A. & M. N. H. 1872, vol. ix. 

 p. 417, pi. xxii. figs. 1-6, 11-17. Loc. Shetland Isles. 

 Distinguished from T. cranium by the absence of liamates. 



Schmidt's genus Graniella is defined as a corticate Tetillaj 

 a rind according to Schmidt being absent in the latter genus ; 

 but since we have shown its decided presence in T. cranium^ 

 it becomes highly doubtful whether it is really absent in the 

 remaining species ; I have therefore reunited (■raniella \\\X\\ 

 Tctilla under the common name of Tetilla. 



The absence of liamates from some species of Tetilla is 

 probably a case of degeneration similar to that of the loss of 

 trifid spicules in the geodinc sponge Camimis, or of ancho- 

 rates from Schmidt's s])ccies Dirrhopalum clopetariunij with 

 regard to which Mr. S. O. Ridley *, in his exhaustive paper 

 on his genus Dlrrhoi)alum, confirms Schmidt's statement as 

 to their absence, though not in the case oi D. yymnazon, where 



* "On the Genua Plocamia, Scluuidt," by Stuart O. Ridley, .Journ. 

 Linn. Soc. vol. xv. p. 47G. 



