REPOE.T ON THE TETKACTINELLIDA. 
91 
pointed or slightly tylote at the extremities, the axis measured only 0‘004 mm. in length, 
the spines 0‘02 mm. 
Colour. — Greyish -white. 
Habitat. — St. lago, Porto Praya, Cape Verde Islands, August 1873; depth 100 to 
128 fathoms. 
Remarks. — This sponge occurs incrusting another fragment of the same species of 
Lithistid {Corallistes masoni) as that which furnished the preceding species of Sphinc- 
trella. That three different species of the same genus should have been obtained at one 
time from the same locality may appear somewhat remarkable. There can, however, be 
little doubt about the fact. The last two species are widely different from each other, not- 
withstanding the occurrence of an unusual feature in the spicules of both, «.e., the annulation 
which occurs in the case of the oxea of Sphinctrella gracilis and of the triod in Sphinctrella 
ornatus. In the latter species microxeas are absent or only rarely present as modifications 
of the triods, which with the microcalthrops form the felted skeleton of the sponge ; in 
Sphinctrella gracilis, on the contrary, microcalthrops and microtriods do not occur, 
but are replaced by microxeas, which form the felted skeleton. The annulated 
microtriods and microcalthrops of the species under description recall the annulate 
microcalthrops figured by Carter as characteristic of the species Tisiphonia annulata, 
Carter.^ They are very similar both in size and general appearance, and it would seem 
probable that Carter’s species, which is from the Gulf of Manaar, may be assigned to the 
genus Sphinctrella. Carter also calls attention to the resemblance of the annulated 
microcalthrops to certain fossil spicules from the Haldon greensand, described by h im 
under the name of Monilites haldonensis.^ There exists no doubt a striking similarity 
both in size and form between the fossil and the recent spicules, but in the absence of 
associated spirasters it would be hazardous to do more than point this out. 
The cloaca does not appear in Sphinctrella ornatus to be separated from the 
excurrent canals by a special membrane, or if so, the apertures in it are of so large a 
diameter as to render it inconspicuous. 
Genus 4. Characella,^ Sollas. 
Theneidse with spicules like those of Pcecillastra, but distinguished by the absence of 
calthrops from the choanosome. 
’ Ann. and Mag. Nat. Hist., ser. 5, vol. vi. p. 494, pi. v. fig. 28, 1880. 
^Ann. and Mag. Nat. Hist., ser. 4, vol. vii. p. 132, pi. ix. figs. 44, 45, 1871. 
® XX'O; 0 , a pointed stake. 
