REPORT ON THE TETRACTINELLIDA. 
55 
II. Microsclere. 4. Sigmaspire, surface raised into irregular rounded transverse 
ridges, 0’035 by O'OOG mm. 
Habitat. — Florida ; depth, 100 to 123 fathoms (not from ‘Iceland ?). 
Remarks. — This is probably a good species, distinguished by the large and character- 
istic sigmaspire. Schmidt assigns specimens frorn Iceland to this species, but the 
mounted spicules in the British Museum do not support this determination. 
Craniella zetlandica (Carter). 
Tetliya zetlandica, Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. ix. p. 417, pi. xxii. figs. 
1-6, 13-17, 1872. 
Tetliya cranium, var. zetlandica, Norman, Bwk., Mon. Brit. Spong., vol. iv. p. 39, 1882. 
Sponge similar to Craniella cranium. 
Spicules. — I. Megascleres. 1. Somal oxea, 4’6 by 0'06 mm. 2. Cortical oxea 
IT by 0'05 mm. 3. Protrisene, rhabdome 5’3 by 0‘018 mm. 4. Anatrisene, rhabdome 
5‘3 by 0'025 at the cladose end, rapidly diminishing to 0’013 mm.; cladi 0‘08 mm. long, 
chord 0*013 mm. 
II. Microscleres absent. 
Habitat. — Shetland Islands. 
Remarks. — This species very closely resembles both Craniella simillima, Bwk., and 
Craniella cranium, Lmk. From the latter it differs chiefly in the absence of sigmaspires, 
which are not present at any stage of its existence ; that no other notable differences are 
correlated with this is a remarkable fact, suggesting grave suspicions as to the value of 
the sigmaspires for classificatory purposes. That their presence or absence is of sufficient 
value, at least for specific distinction, however, will, I think, be admitted, and we may, 
therefore, fairly recognise the validity of Carter’s species, Tethya zetlandica, as opposed to 
Tethya cranium. When we come to compare Craniella simillima with Craniella 
zetlandica the case is different; neither of these species possesses sigmaspires, and the only 
characters on which a distinction can be made are the relative dimensions of the spicules. 
In the Challenger specimens of Craniella simillima the somal oxeas range from 2*85 by 
0*028 to 3*37 by 0*047 mm., the cortical oxeas measure 1*4 by 0*04 mm., the latter are 
therefore larger than the corresponding spicules in Craniella zetlandica, the former smaller. 
Whether this difference is sufficient for the distinction of species appears to me very doubtful. 
Fangophilina submersa, 0. Schmidt. ^ 
FangopMlina submersa, 0. Sch., Spong. Meerb. Mexico, p. 73, pi. x. fig. 3, 1880. 
This evidently very interesting species is insufficiently characterised by Schmidt. It 
recalls in some sort the general appearance of Cinachyra barbata, Sollas. 
Habitat. — Caribbean Sea. 
