REPORT ON THE TETRACTINELLIDA. 
47 
Connies, which are united by ridges, circumscribing shallow depressions, in each of which 
is situated a large pore. Size 24 by 12 mm. 
Skeleton. — I. Megascleres. 1. Oxea, 4 mm. and over by 0'008 mm. 2. Protrisenes 
of two kinds ; one with three equal cladi, rhabdome O'OOl mm. in diameter, cladi 
0'004 mm. long; the other with two shorter cladi and one longer, rhabdome 0'003 mm, 
in diameter, longer cladus 0‘04 mm., shorter cladi 0'02 mm. long. 3. Anatrisene, 
rhabdome 0’005 mm. in diameter; cladi 0‘025 by 0‘005 mm. 
II. Microscleres. 4. Sigmaspire, spined on the outer side of the spire, 0'017 mm. 
long. 5. Splneraster, consisting of rosette-like groups of fifteen to twenty radiately 
arranged fusiform actinees. •» 
Canal System. — Flagellated chambers, 0'03 by 0'02 mm.; main excurrent canals six 
in number, radiately arranged. 
Habitat. — Japan ; depth % 
Rennarks. — This sponge is fully described and illustrated by the author ; it is 
distinguished by its small spined sigmaspires, and the regular arrangement of the six 
main excurrent canals. The spherasters are unique, and one feels a certain suspicion 
that they may not belong to the sponge. Lampe’s description would lead one to infer 
that the canal system is aphodal ; this is not the case in any Tetilla I have examined, 
nor in any sponge with a collenchymatous mesoderm, such as this is stated to possess ; 
so that there may be some error in this observation. Both ova and spermatozoa were 
observed. 
Tetilla polyura, 0. Schmidt. 
Tetilla polyura., O. Schmidt, Spong. Atlant. Gebiet., p. 66, pi. vi. fig. 8, 1870. 
„ „ (1) Vosmaer, Spong. “ Willem Barents” Exped., p. 9, pi. i. figs. 1-3; pi. v. figs. 
3-7, 1885. 
Habitat. — Iceland, 85 fathoms (0. Schmidt). Arctic Ocean; lat. 77° 7' N., long. 
49° 37' E. ; lat. 75° 20' N., long. 46° 40' E. ; lat. 72° 36' N., long. 24° 57' E. ; from 140 
to 170 fathoms (Yosmaer). 
Remarks. — The possibility of Tetilla sandalina, n. sp., being identical with this species 
has been already alluded to (p. 3). Schmidt’s description is inadequate, and the mounted 
spicules of Schmidt’s sponge in the British Museum are too fragmentary for satisfactory 
comparison. The protrisene presents two shorter cladi about 0'07 mm., and a third 
longer cladus about 0T8 mm. long. The sigmaspires measure about 0'02 mm. in length. 
Vosmaer’s illustrations of the sponge, which he thinks may belong to Schmidt’s species, 
are excellent ; unfortunately he gives no measurements of spicules. 
