REPORT ON THE HEXACTINELLIDA. 267 



also under a magnifying power of ten and twenty diameters, in his pi. xxi. figs. 8, 9. 

 In the course of his paper he describes the one piece in the following words : — " An 

 irregular network, more or less bent, with subquadrate meshes, sometimes crossed by 

 oblique threads," while, with regard to the other he said : — " The meshes of the network 

 are on nearly the same plane, and of a more regular square form, with a short pointed 

 spiculum projecting from one side of each decussation of the threads like the teeth of 

 a harrow." 



Some years later Bowerbank also communicated the results of his examination of the 

 same object. He considered the two skeletal fragments which had been described 

 and separated by Owen to be parts of one and the same sponge. The harrow-like 

 network of siliceous beams represented by Owen in his figs. 8 and 9, with its regular 

 quadrate meshes and pointed teeth projecting perpendicularly from the crossing points, 

 he regarded as the dermal skeleton, under which only the irregularly formed inner body 

 skeleton was said to have lain. After more precise examination of both pai-ts by the 

 aid of stronger magnifying powers, Bowerbank saw that the beams of the fragment 

 regarded by him as belonging to the inner body skeleton were completely perforated by 

 a manifest axial canal, and were richly covered externally with fine spines, while the 

 beams of the (dermal) skeletal network which formed quadrate meshes appeared solid and 

 smooth. Only the teeth projecting at right angles to the knob points appeared rough, 

 Bowerbank, moreover, drew attention to the fact that the rough teeth stand at right 

 angles to the plane of that quadrate network not only on its outer side, but on both 

 surfaces. 



To this form, the body and dermal skeletons of which he had examined in the above 

 two fragments, Bowerbank gave the generic designation Farrea, in honour of the fortunate 

 possessor of that specimen of Etiplectella cucumer in whose root-tuft the forms were 

 found, and he added to this the specific name of occa on account of the great similarity 

 of one of the specimens to a harrow.^ In his Monograph of the British Spongiadse 

 (part i. p. 204, 1864), Bowerbank referred his Farrea occa to the sponges with a " canali- 

 culated siliceo-fibrous reticulate symmetrical skeleton," the "fibres" of which being 

 " composed of concentric layers of solid sUex, mth a continuous central canal," and he 

 added : — "The fibres in Farrea occa are rather coarse, abundantly tuberculated, and the 

 mode of reticulation is rectangular." The inner body skeleton referred to in this latter 

 description is figured in pi. xv. fig. 277, and in the description of the plate is referred 

 to as "simple fistulose siliceous fibre, spinulated"; while the solid and smooth network 

 of beams which, in Bowerbank's opinion, belongs to this sponge and constitutes its 

 dermal skeleton, is figured on pi. xxi. fig. 311, and in the description of the plate is 

 referred to as a "quadrilateral siliceo-fibrous network showing the double series of 

 entirely spined spicular organs projected from its angles." 



1 Lat., occa. 



Mas 



