TETRAXONIDA 



281 



main skeleton contain only feebly developed spicules, measuring 0-052 by 0-002 mm., 

 while the dermal skeleton contains only normal spicules, measuring o-o6 by o-oo6 mm. 



In the same way, the inadequacy of Siphonochaliua, as a genus for the reception of all 

 tubular Chalininae, is shown by the fact that, while the remainder of the specimens are 

 sub-ramose or lobate, one is erect and tubular, with an apical osculum and a deep cloaca 

 running the length of the body, and two accessory lateral oscula near the base. 



Distribution. Chile. 



Callyspongia fusifera (Thiele) (Plate LII, fig. i ; Figs. 15, 16). 



Chalina fusifera, Thiele, 1905, p. 476, figs. 15, 32, 95. 



Occurrence. St. WS 77: Falkland Islands, 1 10-113 ™-'^ St. WS 86: Falkland Islands, 157-147 m. 



Remarks. The specimen assigned to this species is palmo-digitate (see Plate LII, 

 fig. i) and comparison of the figure given with that given for the holotype (Thiele, loc. 

 cit., fig. 15) shows that the two specimens have a similar appearance although the shape 



a be 



Fig. 15. Callyspongia fusifera (Thiele). Falkland Islands specimen. «, dermal skeleton, x 100; 

 b, main skeleton, x 100; c, oxeote, x 400; ec/i, echinating tufts of spicules seen in section. 



is not identical. On the other hand, the arrangement of the dermal skeleton and the 

 shape of the spicules diff^er considerably in the two specimens. Through the kindness 

 of Dr W. Arndt, I have been able to examine a piece of the holotype and have found that 

 the dermal skeleton is a close-meshed reticulation showing an incipient differentia- 

 tion into primary and secondary meshes. The main skeleton is a coarse and large-meshed 

 reticulation with multispicular primary fibres and unispicular secondary fibres. The 

 spicules are o-o6 mm. long and rounded at the ends, although not forming pure 

 strongyla. The dermal skeleton of the present specimen does not show so marked a 

 differentiation into primary and secondary fibres even as the holotype. The main 

 skeleton is a close-meshed reticulation with bispicular primary fibres and unispicular 

 secondary fibres, and the dermal skeleton is echinated at the nodes by tufts of spicules 

 projecting from the ends of the primary fibres of the main skeleton. The spicules are 



