CRINOIDEA 25 



elsewhere from the Bay of Biscay to the Canaries, and from the 

 West Indies (off Martinique). Bathy metrical distribution ca. 

 600-2100 metres. 



[Family Thalassometrid^] 



Of this family, the characters of which appear from the key 

 on p. 16, three genera are represented in the N.E. Atlantic, and 

 may well be supposed to occur also in the deep sea off Ireland. 

 These are : Crotalometra A. H. Clark, with the two species 

 Cr, j^orrecta (P. H. Carpenter) (s^ti. Antedon porrecta P. H. Carp.), 

 known from the Bay of Biscay, 1480 m. ('' Talisman ") and from 

 off Ascension, 768 m. ("' Challenger "), and Cr. flava (Koehler) 

 (syn. Antedon flava Koehler) from the Bay of Biscay, 1410 m. 

 (" Caudan "), and 25° 39' N., 18° 22' W., 882 m. (" Talisman ") ; 

 Stiremetra A. H. Clark, with the species St. lusitanica (P. H. 

 Carpenter) (syn. Antedon lusitanica P. H. Carp.) from off Portugal 

 to the Canaries, ca. 915-2165 m. (■" Porcupine ", " Talisman ", 

 " Princesse Alice "), and Thalassometra A. H. Clark, with the 

 species Th. omissa (Koehler) (syn. Antedon omissa Koehler) 

 found off Teneriffe, Canaries, 1330-1340 m. (•' Princesse Alice "), 

 only a single specimen known. The three genera are thus dis- 

 tinguished : 



1. Arms usually 10. rarely as many as 13 . . . .2 



,, ,, 20, proximal arm-joints smooth 



Crotalometra A. H. CI. 



2. Proximal arm-joints smooth, but with a more or less prominent 



median keel ..... Stiremetra A. H. CI. 



Proximal arm- joints more or less thickly studded with spines, 

 especially on the edges ; no median keel 



Thalassometra A. H. CI. 

 The tw^o species of Crotalometra are thus distinguished : 



Cirri with 40-50 joints, the longest of which are only slightly 

 longer than broad ; proximal arm- joints not with the distal 

 edge turned outwards and produced Cr. porrecta (P. H. Carp.) 



Cirri with ca. 30 segments, the longest of which are ca. twice as 

 long as broad ; proximal arm -joints with the distal edges 

 turned outwards and produced . . Cr. flava (Koehler) 



IV. Family Antedonid.^ 



Free, unstalked Crinoids. Cirrus -sockets not bordered by a 

 horseshoe-shaj^ed raised rim. Arms 10, dividing on the second 

 post-radial joint (the axillary ).i 



^ This diagnosis, combined with the eliaracters given in the key- 

 to the famihes of Crinoids of the European seas (p. 16), is sufficient for 



