EEPORT ON THE MONAXONIDA. 93 



summit. The scattered tylostylote spicules of Cladorhiza similis and Cladorhiza 

 inversa are replaced by styli. 



Imbedded in the lower surface of the sponge was a large, spherical, hard, brown body ; 

 probably some parasite, perhaps encysted. This illustrates well the protective use of the 

 dense external armour present in Axoniderma mirahile, nobis, and absent in this species. 



Locality.— ^tn.tio^ 264, August 23, 1875 ; lat. 14° 19' N., long. 152° 37' W.; North 

 Pacific Ocean; dej)th, 3000 fathoms; bottom, red clay; bottom temperature, 35°-2. One 

 specimen. 



Cladorhiza similis, Eidley and Dendy (PL XX. fig. 7; PI. XXI. figs. 5, 5«, bh, 18). 



1886. Cladorrhiza similis, Eidley and Dendy, Ann. and Mag. Kat. Hist., ser. 5, vol. xviii. p. 343. 



The sponge (PI. XX. fig. 7) has assumed the " Crinorhiza " form, and consists of a cap- 

 shaped, conical head, perched on the end of a stem or root, which appears to have been 

 broken ofi" short, so that its proper length cannot be ascertained. From the margin of 

 the cap project a considerable number of long spicular processes, radiating outwards and 

 downwards. The apex of the sponge is pointed, and apparently devoid of short spicular 

 processes. The lower surface is shallowly concave, and only just G mm. in diameter. 

 Colour in spirit dirty yellow. 



Skeleton. — AiTanged as usual in " Crinorhiza " forms. 



Spicules. — (a) Megasclera; (l) very long, slender styli of the usual type; (2) short, 

 fusiform tylostyli (PI. XXI. figs. 5, 5«, 5?^), with peculiarly shaped heads ; usually 

 very sharply pointed, and with the head and neck inclined at an angle to the main 

 shaft. These spicules vary greatly in size, measuring from 0*21 to 0'6 mm. in length, 

 usual thickness about 0'0157 mm. They occur chiefly scattered about near the surface 

 of the sponge, where they are very thickly placed, and apparently represent in function 

 the large, five-toothed, special protective spicules of Axoniderma mirahile. They are also 

 found in the skeleton-fibres. (&) Microsclera; we have seen only the anisochelse, but 

 in our anxiety not to destroy such a unique and so small a specimen, it is not improbable 

 that we have overlooked the sigmata. The anisochela (PI. XXI. fig. 18) is of the usual 

 Cladorhiza type. The shaft is curved and much expanded laterally towards the 

 larger end, and there are three teeth at each extremity. Length about 0'03 mm. 



It will be seen from the foregoing description that, as regards external appearance, this 

 species comes very close indeed to Axoniderma mirahile, nobis ; it differs, however, 

 in the replacement of the additional microsclera, so characteristic of the latter, by small 

 tylostyli, and also in the absence, if they be really absent, of the sigmata. The anisochelse 

 are, however, almost identical both as regards shape and size in the two species. 



Locality. — Station 281, October 6, 1875; lat. 22° 21' S., long. 150° 17' W.; South 

 Pacific; depth, 2385 fathoms; bottom, red clay; bottom temperature, 34°'9. One 

 specimen in moderately good condition. 



