28 BRITISH SPONGIAWE. 



the forms of Tethya cranium, he will find a so-called 

 variety of that species named acufera, which differs 

 from the typical cranium in exactly the same manner as 

 Geoclia Zetlandica is distinguishable from G. megastrella, 

 namely, by an intermixture of fusiformi-acuate with 

 the usual fusiformi-acerate skeleton spicula. 



Genus 6. PACHYMATISMA, Bow., i, 171 ; n, 3. 



PACHYHATISMA JOHNSTONIA, Bow., ii, 51 ; i, PI. I, figs. 

 15, 17, 20, 21 ; PI. II, figs. 45, 46 ; PI. IV, fig. 93 ; 

 PL VI, figs. 158, 159 ; PL XXIV, figs. 330332 ; 

 PL XXVII, fig. 353 ; in, PL VIII, figs. 17. 



1869 Pachymatisma Johnstonia, Carter. Ann. Nat. Hist., 

 ser. 4, vol. iv, p. 8, pi. ii, figs. 7 18. 



1873 Caminus oscuJatus, Grube. Mittlieil. ii. St. Malo u. 

 Roscoff, &c., p. 132, Taf. ii, figs. 3, 3 a e. 



Procured by me in 1867 in "Will Hellyer," a cave 

 at the most northern point in the British Islands, the 

 headland on the east side of Burrafirth in the island 

 of TJnst, Shetland. This cave, which is always filled 

 by the sea, cannot possibly be entered except in the 

 calmest weather ; and the Sponge having been caught 

 sight of at its furthest extremity, was at length 

 procured, though not without incurring some danger. 

 This is the only instance of its occurrence in Shetland 

 (N.). Budleigh-Salterton (Carter). 



Genus 7. NORMANIA, Bow., in, 258. 



1868 Normania, Bowerbank. In Last Report of Dredging 

 among the Shetland Isles ; Norman on the Porifera 

 (Brit. Assoc. Rep.), 1868, p. 328. 



