8P0NGIIDA. 417 



point of attachment ; the length (horizontal) is 39 millim. (1^ inch), 

 greatest (vertical) thickness 8 millim., average thickness of narrow 

 lobe 2 millim. Colour (in spirit) white ; texture rather firm, harsh 

 (Carter says " tender "). A small aperture, about '3 miUim. in dia- 

 meter, at the end of the shorter lobe is the only perceptible vent. 

 Surface obscurely wrinkled. Spicules as in A. pcmicea, measuring 

 •8 to 1 miUim. by -012 to -018 millim. 



This specimen agrees well in size and in its general and spicular ' 

 characters with those described by Mr. Carter from Ceylon. 



Hab. Prince of Wales Channel, Torres Straits, 5-7 fms. 



Distribution. Basse Eocks, Ceylon, Kerguelen Island {Carter), 

 (Atlantic ?, Garter, I. c). 



53. Tedania digitata, varr. 



Reniera digitata, Schmidt, Adr. Meer. p. 75, pi. vii. fig. 11. 

 Reniera ambigua, id. Adr. Meer. Suppl. p. 39, pi. iv. fig. 8. 

 Reniera muggiana, id. Spong. Alg. p. 28. 

 Tedania digitata et muggiana, &rai/, P. Z. S. 1867, p. 520. 



Tedania nigrescens, Schmidt, Adr. Meer. p. 74, is probably not 

 distinct from the above species ; but, as it was not intelligibly de- 

 scribed until after T. digitata, the latter name in any case takes 

 precedence. 



From a comparison 'of the specimens and slides of these different 

 species in the Museum inter se and with Schmidt's descriptions, I 

 come to very much the same conclusion as Schmidt (Atl. Geb. p. 43), 

 viz. that they are all mere varieties. Schmidt's expression is • that 

 it is merely a matter of taste whether they are called species or 

 varieties. The differences in outward form have caused him his 

 greatest doubts as to their identity ; and it is true that, while some 

 specimens bear large lobate elevations, others are massive, and 

 that whereas some have large vents, in others they are all small 

 and scattered. But I find that all agree in a more or less massive 

 habit, cavernous structure, and strongly ridged or papillose surface ; 

 whereas the Atlantic form, T. suctoria, Schmidt, and the Chilian 

 T. tenuicapitata, mihi, have an almost even surface. 



The forms of the spicules are practically the same in all cases, and 

 the micro-spination of the heads of the cylindrical "tibieUa" is 

 undoubted throughout, whereas in the two specified species the heads 

 are quite smooth. 



The Port-Darwin specimens differ decidedly in the proportions of 

 the acuate spicule, as will be seen below, from the rest. None of 

 the varieties pointed out seem to stand out with sufficient distinctness 

 from the rest to receive distinct varietal names. A specimen lately 

 received from Kurrachee agrees essentially with all the above spe- 

 cimens, the spicules being only rather small ; the surface is broken 

 up into a dense mass of slender, almost filifoim processes and 

 lamellar ridges, from 1 to 5 or 6 millim. high. 



2e 



