ON THE SHETLAND CRUSTACEA, TUNICATA, ETC. 831 
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 dermalmembrane. Sarcode 
abundant. Colour, dried, light grey. Habitat. Shetland (Rey. 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. 
os 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, largeand 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 veticulatus, Bow. “Stroma, Shetland, Mr. C. W. Peach” 
(Bowerbank). 
perarmatus, Bow. The type specimen procured 40 miles east of the 
Outer Skerries in 1861. 
membrana, 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. 
subereus (Montagu). Not so common as UW. ficus, to which it is very 
closely allied. 
carnosus (Johnston). Large short-stalked specimens, of the size of a 
large apple, in Dourie Voe. Small specimens with the head about 3 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. 
jicus (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 Voe, 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. | 
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