sponges from the Atlantic Ocean. 237 



Microciona jecusculum, Bk. {op. cit. vol. iii. pi. Ixxxiii. 

 figs. 1-6). 



This sponge was originally described bj Dr. Bowerbank as 

 a " Hymeniacidon'''' [op. cit. vol. ii. p. 198). The spicules 

 are : — a partially spined, large, skeleton acuate ; a smooth, 

 acuate ; pointed, subskeleton acerate ; a small, entirely spined 

 acuate, and an angulate or bow-shaped equianchorate. 



Loc. Island of Harris, Hebrides. 



Two specimens of this thin laminiform sponge were dredged 

 up on board the ' Porcupine,' viz. at station 25, in 374 

 fathoms, near Cape St. Vincent, and at station 61, in 114 

 fathoms, near the Faroe Islands, respectively — the former, of a 

 reddish colour, spreading over the flat surfaces of a piece of Co- 

 rallistes Bowerhanhii^ and the latter, almost colourless, over a 

 Terebratule. Both are characterized by possessing a smooth, 

 acerate, subskeleton-spicule, and a much greater development 

 of the spines round the bases of the two forms of acuates 

 respectively, than in any other part ; while the spicule-illus- 

 trations given by Dr. Bowerbank agree better with the colour- 

 less specimen on the Terebratule than with the red one on the 

 piece of GoralUstes. The spicules in the latter are not so 

 large, the acuate skeleton-spicule less curved towards the 

 base, and the equianchorate larger in the arms and more 

 pointed at the ends, so as, laterally, to resemble a bow, of 

 which the anterior arm of each end, being by recurvation closely 

 approximated at their points, would form the cord or string. 

 In both the tricurvate is absent ; and the subskeleton-spicule, 

 being acerate, smooth, and nearly straight, corresponds more 

 with that of Halichondria plumosa than with that of the 

 Microcionina generally, in which it is acuate. It may be 

 questioned hereafter whether the difi^erences noticed between 

 the above-mentioned forms of M. jecuscidum are sufficient to 

 constitute two species. Colour alone in sponges is seldom of 

 much specific value. 



Microciona longispictdum^ n. sp. (PI. XII. fig. 1, A, and 

 PL XV. fig. 31, a, 5, c.) 



General form thin, laminar, hirsute. Colour tawny. Sur- 

 face hairy. Pores and vents not seen. Spicules of two kinds, 

 viz. skeleton- and flesh-spicules. Large skeleton-spicule 

 long, smooth, curved, thin, globularly inflated or bulbous at 

 the fixed extremity, smooth throughout, 160-1800ths inch 

 long by 2-1 sooths inch in diameter at the bulb (PI. XV. 

 fig. 31, a). Subskeleton-spicule smooth, acuate, curved. 



