REPORT ON THE MONAXONIDA. 167 



regard to its spiculation we have placed it amongst the Axinellidse, although the 

 arrangement of the skeleton is opposed to this view. Such a skeleton is, however, 

 quite capable of giving rise by further development to a typical Axinellid skeleton, and 

 it is possible, judging from its extreme simplicity, that Hyineniacidon represents the 

 starting point from which the more typical Axinellidas have branched off. Were it not for 

 the form of the spicules, which are monactinal instead of diactinal, we should include the 

 genus amongst the Eenierinaa. It differs from most Axinellidi^ in having the spicules of 

 one form only and all of about the same size. 



The genus is characteristicall}^ an inhabitant of shallow water. 



Hymeniacidon caruncula, Bowerbank (PI. XXXIII. fig. 3). 



1864. Hymeniacidon caruncula, Bowerbank, Mon. Brit. Spong., vol. i. p. 191, pi. xxxv. fig. 372 ; 



vol. ii. p. 166; vol. iii. pi. xxxii. figs. 1-4; vol. iv. p. 81. 

 1867. Reniera caruncula. Gray, Proc. Zool. Soc. Lond., p. 518. 

 1870. Amorpliina caruncula, Schmidt, Spoiig. Atlaut. Gebiet., p. 76. 



There are in the collection two specimens of this common British sponge from 

 the Cape Verde Islands ; both are rather small and with uneven (conulose) surface 

 (PI. XXXIII. fig. 3) ; the proportion of horny matter in the skeleton is very con- 

 siderable. As the species is already sufficiently well known we do not propose to give any 

 further description of it in this place. 



Locality. — St. Vincent, Cape Verde Islands ; shallow water. Two specimens. 



Habitat. — British Isles ^ (Bowerbank); Cape Verde Islands (Challenger); Port 

 Jackson (Ridley, "Alert"). 



Hyineniacidon sp. 



We have to record from Station 313 a single, soft, massive specimen, in bad 

 condition, which seems to be referable to this genus but is not sufficiently well 

 characterised to merit a specific name. The surface, where preserved, is smooth, and the 

 skeleton consists of very sparsely disposed columns of smooth stylote spicules united 

 together by a considerable proportion of horny matter ; the same spicules also occur 

 loosely scattered. 



Spicides. — Of one form only, viz., smooth, gradually sharp pointed styli, measuring 

 about 0-43 to O'S by 0-0126 mm. 



Locality.— ^taXion 313, January 20, 1876 ; lat. 52° 20' S., long. 67° 39' W.; south- 

 east of Patagonia; depth, 55 fathoms; bottom, sand; bottom temperature, 47°'8. One 

 specimen. 



1 " One of the regular tide-mark sponges of our southern and western coasts," Norman (Mou. Brit. Spong., vol. iv. 

 p. 81). 



