330 ESCHAKIDyE. 



of course the mouth is sunk below the surface. In few 

 cases is the appearance of a species so completely changed 

 by age and the progress of calcification (Plate XXXIX, 

 fig. 5). 



Habitat. On stones^ and Porella compressa, from deep 

 water. 



Locality. '' About 25 miles north of the island of 

 Unst, the most northern of the Shetland group/' very 

 rare (A. M. N.). 



Geographical Distribution. Bergen (A. M. N.) : 

 lat. 73° 41' 6", long. 22° 58' 30'', in 220 fathoms (Dutch 

 Arctic Exped.). 



I have no hesitation in referring this species to the 

 genus Porella. It is closely allied to P. concinna; it 

 presents the very marked shape of the mouth, slightly 

 modified in its proportions, which is characteristic of that 

 species, while at the same time there is a complete paral- 

 lelism between the two forms in the mode in which the 

 orifice is developed. 



c. Zoarium erect ; branches compressed. 

 Porella compressa, Sowerby, 



Plate XLV. figs. 4-7 ; woodcut, fig. 14. 



PoRUs CERViNus, Borlttse, N. Hist. Cornwall, 240, pi. xxiv. fig. 7. 



MiLLEPORA COMPRESSA, Sowerby, Brit. Miscel. i. (1806), 83, pi. xli. 



Oellepora cervicornis, Flem. Br. An. 532: Johnston, B. Z. ed. 2, 298, 

 pi. liii. (Jide Alder, who had examined the type specimen in 

 the British Museum): Couch, Corn. Faun. pt. iii. Ill, 

 pi. XX. fig. 1 : Busk, Ann. N. H, ser. 2, xviii. 32, pi. i. fig. 1: 

 Sars, Eeise Lof. Finm., N. Mag. f. Naturv. vi. 147 (27 sep.) : 

 Alder, Quart. Journ. Micr. Sc. n. s, iv. (1864), 98. 



EscHARA fEKVKORKis, Busk, B.M. Cat. ii. 92, pi. cix. fig. 7, exix. fig. 1 : 

 D'Orbigiii/, Pal. Fran9. L c. 344: Hincks, Devon Cat., Ann. 



