of Recent Brachiopoda. 375 



water to 100 fathoms : obtained by Prof. King from the depth 

 of 30 fathoms at a distance of twenty -five miles from the north- 

 ern coast of Northumberland, and by Laskey by dredging in the 

 depths of the Frith of Forth. This species is found fossil in the 

 Norwich Crag, and in the glacial formation of the Clyde. 



49. Rhynchonella nigricans, Sow. sp., 1846; Proc. of Zool. Soc. 



and Sow. Th. Conch, pi. 71. fig. 81, 82; also Dav. Zool. 

 Proc. 1852. 

 Hab. Foveaux Straits, about five miles N.E. of Ruapuke Island, 

 dredged in 19 fathoms by Mr. F. J. Evans, R.N., New Zealand. 

 Obs. This species is undistinguishable from half-grown speci- 

 mens of the oolitic Rh. concinna, Sow., but probably never be- 

 came so globular as that species is found, when adult. 



4. Family Orthid^e (extinct). 



Arms spiral ; ? destitute of calcareous supports, attached or not 

 by a pedicle. 



5. Family Calceolid^e (extinct). 



6. Family Craniate and Orbiculid^e. 



Shell horny or calcareous, minutely tubular, attached by the 

 ventral valve, or by a pedicle passing through a fissure in it ; no 

 hinge or apophysary system ; animal with its oral arms fixed to 

 a process of the lower (ventral) valve. The lower valve in both 

 Crania and Orbicula correspond to the perforated valve of Tere- 

 bratula, so that while those two genera form an exception to 

 the invariable rule that the shell of the Brachiopod is fixed by 

 means of the ventral valve, they differ very remarkably from 

 other genera in having the oral arms fixed to the ventral or 

 attached valve. 



XII. Genus Crania, Retzius, 1781. 



Shell calcareous, tubular ; ventral or fixed valve with a central 

 process, to which the spiral arms are attached ; dorsal or upper 

 valve free, limpet-like, with two diverging muscular processes. 

 No hinge or calcareous appendage, no perforation for the passage 

 of a pedicle of attachment ; arms fleshy. 



50. Crania ringens, Hceningh., 1828 ; Sow. Th. Conch, pi. 73. 

 fig. 10, 11. 



Hab. Mediterranean in from 40 to 90 fathoms ; also near Sid- 

 ney, New South Wales. 



51. Crania per sonata, Lam. 1819 ; Sow. Th. Conch, pi. 73. fig. 9. 

 Hab. India. 



