332 REPORT 1868. 



Hymeniacidon sulpJiureus, Bow. " Shetland, 1864" (Bowerbank in litt.). 



paupertas, Bow. Parasitical on zoophytes from deep water in 1861, off 



Out Skerries. 



Cliona celata, Grant. Common in shells. 



Halichondria panicea (Pallas). The encrusting forms very abundant in caves 

 and on stones between tide-marks. A giant specimen, in the form of a 

 roll wrapped round the stem of a Laminaria, measures 13 inches long 

 and 3 inches in diameter. 



coatita (Grant). " Shetland, 1864" (Bowerbank in litt.). 



forceps, Bow. On the Outer Haaf, off Unst, in 1864 and 1868. The 



" forcepiform " spicula in this species are very remarkable, and at once 

 distinguish the species. They resemble very slender hair-pins, the bow 

 very narrow, the pins very long, finely spinulous, and approaching each 

 other at the points. 



simplex, Bow. " Shetland, Mr. C. W. Peach " (Bowerbank). 



incrustans (Esper). Abundant, coating the sides of Halse Hellyer, 



Burrafirth, growing side by side with H. panicea and Isodictya fucorum, 

 the three species intermingling with each other. 



Dickiei, Bow. On Cettepora cervicornis, dredged in deep water, 1863. 



Patersonii, Bow. Rare, one specimen found in 1867. 



" falcula, Bowerbank, n. sp. Sponge massive, sessile. Surface uneven, 



minutely spinous and reticulated. Oscula simple, dispersed. Pores in- 

 conspicuous. Dermal membrane pellucid, furnished with a stout irre- 

 regular polyspiculous network. Skeleton rete polyspiculous, very ir- 

 regular and diffused ; spicula fusiformi-acuate, slender and long. In- 

 terstitial membranes tension-spicula same as those of the skeleton but 

 smaller, few in number. Eetentive spicula trenchant, contort, biha- 

 mate, stout and large, very few in number. Gemmules membranous, 

 aspiculous. Colour in the dried state cream-white. Habitat. Shetland. 

 Rev. A. M. Norman. Examined in the dried state." 



" mululus, Bowerbank, n. sp. Sponge sessile, massive. Surface 



openly reticulated. Oscula simple, very numerous. Pores inconspicuous. 

 Dermal membrane spiculous ; tensiori-spicula acuate, slender, very 

 nearly as long as those of the skeleton, few in number ; also tricurvato- 

 acerate, very long and slender, nearly straight, sometimes flexuous ; 

 central curve abruptly angulated or looped, rather numerous ; retentive 

 spicula dentato-palmate, equianchorate, very minute and symmetrical, few 

 in number. Skeleton equably reticulate ; rete stout and polyspiculous ; 

 spicula subattenuato-acerate, stout and strong, moderately long. Inter- 

 stitial membranes pellucid, furnished with the same forms of spicula as 

 the dermal membrane but more sparingly. Colour in the dried state 

 light brown. Habitat. Shetland, 96 fathoms (Rev. A. M. Norman). 

 Examined in the dried state." 



scandens, Bow. The type specimen, dredged in 1861 in deep water 



off the Out Skerries. It is a minute species, which encrusts the stems 

 of Sertularian. Zoophytes. 



Batei, Bow. " Shetland?, Mr. Spence Bate" (Bowerbank). 



- Hyndmanni, Bow. " Shetland, 1864 " (Bowerbank in litt.). 



albula, Bow. " Shetland, deep water, Barlee " (Bowerbank). 



inornata, Bow. " Shetland, Mr. C. W. Peach" (Bowerbank). 



Isodictya varians, Bow. "Shetland, Mr. Barlee" (Bowerbank). 



jugosa, Bow. The type specimen, found in deep water off the Out 



Skerries. 



