Otf THE SHETLAND CRUSTACEA, TUNICATA, ETC. 331 



acerate, very long- and slender, flexuous, dispersed singly, or fasciculated, 

 fasciculi frequently polyspiculous : external defensive spicula the larger 

 ones arising from the projection of the distal extremities of the skeleton 

 spicula through the dermal membrane; the smaller ones attenuato- 

 spinulate, entirely spined, basal bulb often coronulated spinously. Ske- 

 leton spicula spinulate, very long and large, distal end usually projected 

 through the dermal membrane. Basal membrane pellucid ; tension-spi- 

 cula same as those of the dermis, dispersed singly, few in number ; in- 

 ternal defensive spicula same as those of the dermal membrane. Sarcode 

 abundant. Colour, dried, light grey. Habitat. Shetland (Rev, A. M. 

 Norman). Examined in the dried state." 



Hymedesmia radiata, Bow. The type specimen found in 1864; again pro- 

 cured in 1867. 



Zetlandica, Bow. The type found by Mr. Barlee, and taken by myself 



on stones from the Haaf, 1863. 



" occulta, Bowerbank, n. sp. Sponge parasitical, coating. Surface 



irregular, abundantly hispid. Oscula simple, dispersed. Pores incon- 

 spicuous. Dermal membrane abundantly spiculous; tension-spicula 

 acerate, large and long, dispersed; retentive spicula bidentate equi- 

 anchorate, large and stout, numerous, dispersed. Skeleton fasciculi mul- 

 tispiculous ; spicula very numerous, same as those of the dermal mem- 

 brane with an admixture of stout fusiformi- acerate ones. External 

 defensive spicula attenuato-acuate, size various ; large ones basally 

 spined ; smaller ones entirely spined. Colour milk-white. Habitat. 

 Shetland, 96 fathoms (Rev. A. M. Norman). Examined in the dried 

 state." 



Hymeniacidon reticidatus, Bow. " Stroma, Shetland, Mr. C. W. Peach " 

 (Bowerbank). 



perarmatus, Bow. The type specimen procured 40 miles east of the 



Outer Skerries in 1861. 



tnembrana, Bow. The type specimens on the underside of stones 



between tide-marks, near Lerwick, 1861. 



mammeatus, Bow. Two specimens in 1868. 



viridans, Bow. " Shetland, 1864 " (Bowerbank in litt.). 



lingua, Bow. A very large species procured in very deep water, Out 



Skerries and Unst, in 1864 and 1867. 



floreus, Bow. On roots of a Fucus, extreme low water, spring tides, 



Out Skerries, 1861. 



siibereus (Montagu). Not so common as M.ficus, to which it is very 



closely allied. 



carnosus (Johnston). Large short-stalked specimens, of the size of a 



large apple, in Dourie Yoe. Small specimens with the head about ^ of 

 an inch in diameter, elevated on a slender footstalk about an inch long, 

 but at other times almost sessile, in 40-50 fathoms, 5-8 miles east of 

 the Isle of Balta. 



ficus (Esper.). Common, coating univalve shells, and generally inha- 

 bited by hermit-crabs, in moderately deep water. 



[Hymeniacidon gelatinosus, Bow. Dr. Bowerbank gives the locality 

 of the type specimens of this species as " Dourie Yoe, Shetland." This 

 is a mistake ; they were from under a stone between tide-marks at Cul- 

 lercoats, Northumberland. The error doubtless arose from the circum- 

 stance that at the same time there were sent to him with this species 

 specimens of Hymeniacidon carnosus, which were from Dourie Voe.] 



2 A2 



