270 THE VOYAGE OF H.M.S. CHALLENGER. 



Carter distinguished them as body skeletons of tivo dij^erent s2Jecies which he named 

 Farrea occa, Bowerbank, and Farrea densa. 



Carter confined the name Farrea occa, which had been applied to both parts (taken 

 together), to the siliceous network (regarded by Bowerbank as a dermal skeleton), which 

 consists throughout of one layer, surrounds exactly square meshes, and bears at the 

 intersections rough conical pegs on both sides. In justification of this, Carter notes that 

 only this skeletal portion in reality resembles a harrow (occa), and that it had therefore 

 been specially considered by Bowerbank in applying the name. 



In his examination of this species {Farrea occa, Bowerbank), besides using some of 

 the fragments collected during the " Porcupine" Expedition, and the specimens studied 

 by Saville Kent, Carter also employed the fragments which had been obtained from the 

 basal tuft of the beautiful Euplectella cucumer studied by Owen. He was, however, 

 only able to procure completely macerated and greatly eroded specimens, and accordingly 

 could not study the spicules that occur freely on the soft parts. Yet he believed that 

 some spicules which were casually included here and there in the continuous framework 

 of beams might with probability be interpreted as belonging to Favrea occa. With 

 regard to the formation of central canals in the beams of the siliceous framework Carter 

 was convinced from the direct examination of these numerous remnants of Farrea occa, 

 that the entire network of beams, with its rectangular meshes, had not originally possessed 

 a continuous canal system, but, as this arose by the amalgamation of isolated hexradiate 

 sjiicules, it at first consisted merely of the separate hexradiate canals, which terminated 

 blindly at the six extremities, and belonged, of course, to the individual hexradiate 

 spicules. These separate axial canals corresponding to the individual hexradiate spicules 

 usually became very manifest after the death of the animal. On account of internal 

 absorption or solution they are specially wide and striking, and this points to a previous 

 more prolonged maceration of the dead sponge. 



A sponge described by Carter under the designation of Farrea infundibidiformis, 

 from the Caribbean Sea, presents a small funnel-like body, with a much widened thin 

 margin, having an opening of about 2^ cm. in diameter, and with a solid round stalk of 

 about 1 cm. in length and ^ cm. in thickness. The sponge is attached to its stratum 

 by means of the somewhat expanded inferior extremity of the stalk. The skeletal frame- 

 work of the solid stalk consists of a dense lattice- work, with more or less distinctly 

 defined rectangular meshes, and is continuous wdth the skeleton of the funnel-like j^late, 

 so that in the middle of the plate a rectangular lattice-work remains, while more irregular 

 networks of fibres extend over the two surfaces. The beams of the rectangular lattice- 

 work are beset with small spines, those of the irregular network of fibres exhibit still 

 finer spines and bear numerous simple, hexradiate, lateral spicules. In such soft i^arts 

 between the foramina of the siliceous network as were visible in the di'ied condition, 

 Carter found numerous floricomes with minute laterally spinose terminal knobs. 



