226 ECHINODERMS OF THE BRITISH ISLES 



2. Arm spines fairly long, not strongly appressed. Teeth rounded, 



with hyaline edge .... Ophioconis Liitken 



Arm spines very short, strongly appressed. Teeth small conical, 



of the same shape as the mouth papilla? .... 3 



3. Mouth shields covered with granules . Cryptopelta H. L. Clark 

 Mouth shields naked . . Bathypectinura H. L. Clark 



Ophioderma Miiller and Troschel. 

 (Syn. Ophiura Lyman, non Lamarck.) 



This genus, so very easily recognised by its double genital 

 slits, is represented in European seas by only one species, 0. 

 longicauda (Retzius). It is known as far north as La Rochelle 

 on the French coasts ; it is common in the Mediterranean, and 

 occurs along the African coasts as far south as Senegal, and also 

 at Madeira and the Azores. It is a large, robust form, attaining 

 a size of ca. 25 mm. diameter of disk, with the arms ca. 100- 

 150 mm. long, of rather strictly littoral habits, probably not 

 descending beyond ca. 70 metres. 



Cryptopelta H. L. Clark. 



Only one species of this genus known from European seas, 

 viz. Cr. brevispina (Ludwig) (Syn. Ophioconis brevispina Ludwig). 

 Till recently only a single specimen was known, found off Naples 

 (depth unknoAvn) ; another specimen has now been taken off the 

 N.W. coast of Morocco, 145 m. It will doubtless prove to be more 

 widely distributed in the eastern Atlantic. It is a small form, 

 easily recognised through the whole underside of disk, together 

 with jaws and mouth shields, being covered with granules. 



Bathypectinura H. L. Clark. 



Only one species, B. elata (Koehler) (Syn. Pectinura elata 

 Koehler), known from European seas. It has been found at 

 25° 2' N., 19° II' W., 2325-2518 m. (" Talisman ") ; 34° 59' N., 

 33° 1' W., 2615-2865 m., and 35° 46' N., 8° 16' W., 2055 m. 

 (" Michael Sars "), and may well be expected to occur also in the 

 deep water off the British coasts. It is a large form, attaining a 

 size of ca. 30 mm. diameter of test, with a length of arms of ca. 

 100 mm. Besides the naked radial shields and mouth shield it 

 usually has some other naked plates near the edge of the dorsal 

 side and on the under side of the disk. A characteristic feature 

 is the large size of the first pair of tentacle scales. 



The genus Pectinura Forbes is also represented in European 



