292 ECHINODERMS OF THE BRITISH ISLES 



Gill-cuts at edge of peristome rather obsolete ; globiferous pedi- 

 cellaria3 with or without side teeth on the valves, never with 

 dumbbell -shaped spicules ...... 3 



3. Globiferous pedicellaria3 with teeth on both sides of the valves, 

 below the end tooth ; head directly attached to the end of the 

 stalk, without a neck. Spicules simply C-shaped 



I. Fam. Echinidce 



Globiferous pediccllariac without side teeth on the valves ; head 

 attached to the end of the stalk by means of a distinct neck. 

 Spicules with branched ends . III. Fam. Strong ylocentrotidce 



[Fam. Temnopleurid^] 



Test with grooves or pits in the horizontal sutures, or with 

 the plates ornamented by depressions or indentations in the 

 tubercle bases, rarely (in some small deep-sea forms) without any 

 such special marks. Tubercles crenulate or smooth. Gill-cuts 

 small. Globiferous pedicellarise of very different character. 



This family is divided into two subfamilies, one the Temno- 

 pleurince, characterised through having deep pits at the ends of 

 the horizontal sutures and the plates united by small knobs and 

 sockets, the other, the T emnechinince (or Trigonocidarince), with 

 no sutural pits, at most some low sutural depressions, but usually 

 with the plates ornamented by grooves or indentations in the 

 tubercle bases, the plates not united by knobs and sockets. 

 While the first of these subfamilies is confined to the Indo- 

 Pacific, the Temnechininse have representatives also in the 

 Atlantic, namely the following three genera : Trigonocidaris 

 A. Agass., with the species Tr. albida A. Agass., known from the 

 Bay of Biscay (" Caudan ") and off the Azores and Madeira 

 (" Princesse Alice "), further from the West Indies and the Indo- 

 Pacific ; bathymetrical distribution ca. 200-900 m. ; Genocidaris 

 A. Agass., with the species G. maculata A. Agass. (Syn. Temne- 

 chinus maculatus (A. Agsiss. ), Arbacina Pallaryi Gauthier), known 

 from the Mediterranean, the African coast down to Congo, the 

 Azores, the West Indies, and the east coast of N. America ; 

 bathymetrical distribution, ca. 20-420 m. ; Hypsiecliinus Mrtsn., 

 with the species H. coronatus Mrtsn., known only from S.W. of 

 Iceland and the Denmark strait, 810-1440 m. It is quite 

 probable that all these three forms will be found to occur also 

 off the British coasts. They are thus distinguished : 



1. A single large, round plate covers the whole periproct. Base 

 of the primary tubercles more or less deeply indented. Globi- 

 ferous pedicellariae with a single tooth, on one side only. 



