340 ECHINODERMS OF THE BRITISH ISLES 



Monstrous, often most fantastically transformed, specimens 

 occur in great numbers in Skagerrack. 



In British seas this species is known from all along the west, 

 north, and east coasts, but is not recorded from the south coast. 

 It is elsewhere distributed from Lofoten, on the Norway coast, 

 and Iceland to the Mediterranean and S. Africa. Also on the 

 east coast of N. America, but not known from Greenland. The 

 bathymetrical distribution is ca. 5-365 m., and probably more. 

 It is recorded from depths of ca. 860-1280 m. from off the Irish 

 west coast (" Helga "), and even from 3760 m. (" Porcupine "), 

 but there is no certainty that the specimens from these depths 

 are really Br. lyrifera, under which name several different species 

 were hitherto confounded. 



II. Suborder. Meridosternata Loven. 



First ^lair of plates in the posterior interambulacrum placed 

 one behind the other, not much larger than the other plates, 

 forming no conspicuous ventral shield or " sternum " (Fig. 185, 2). 

 Pores simple or double. Fascioles not developed or, at most, 

 very small and inconspicuous. 



The forms belonging to this suborder are exclusively deep-sea 

 forms, usually very fragile, partly of most extraordinary shape. 

 They are divided into four families, two of which are represented 

 in the British seas ; a third, the family Calymnidce, of which only 

 one genus and species is known, Calymne relicta Wyv. Thomson, 

 may perhaps also be found there. The species was taken by the 

 " Challenger " north of the Bermudas in 4770 m. (not at the 

 Azores (Fayal), as erroneously stated in the " Challenger " 

 Echinoidea). 



Key to the families of Meridosternata known from or likely to 

 occur in the British seas. 



1. Mouth horizontally placed on oral surface of test ; no oral 



invagination ........ 2 



Mouth vertical, at the end of a deep oral invagination 



II. Fam. Pourtalesiidce 



2. Second plate in the anterior interambulacra paired ; a marginal 



fasciole present ^ Fam. Calymnidm 



Second plate in all interambulacra single ; no marginal, but 

 usually a subanal fasciole present . . I. Fam. Urechinidce 



1 The presence of a marginal fasciole is probably a character only of 

 generic value ; this also applies to the subanal fasciole in Urechinidae. 

 For description and figures of Calymne relicta see ''Challenger'' Echin., 

 p. 154, PI. XXXIV., and " Ingolf' Ech., ii., p. 53. 



