122 ECHINODERMS OF THE BRITISH ISLES 



Rays not constricted at base ; dorsal skeleton present in the whole 

 length of the rays. Both crossed and straight pedicellariae 



Fam. Pedicellasteridce 



3. Dorsal skeleton irregular, reticulate ; spines single 



IV. Fam. Asteriidce 



Dorsal skeleton larger, fairly regularly arranged plates, covered 



with groups of small spines or graiils .... 4 



4. Adambulacral plates of two alternating sorts ; dorsal side with 



small spines. Tube -feet generally in two series in the distal 

 part of rays .... II. Fam. Zoroasteridce 



Adambulacral plates of one kind only ; dorsal side with small 

 grains or spines. Tube -feet in four series, usually to the end 

 of the ravs ..... III. Fam. Stichasteridoe 



I. Family Brisingid.e 



Rays mostly numerous, rarely only (o) 6-7, long and slender, 

 more or less restricted at the base and sharply defined against 

 the small disk. Dorsal skeleton of rays restricted to their proxi- 

 mal part. Adambulacral and marginal spines long and slender, 

 enclosed in a bag of skin, covered with crossed loedicellarise. No 

 straight pedicellaria?. Tube-feet in two series. 



The sea-stars belonging to this family are mainly deep-sea 

 forms, some of them, at least, strongly phosphorescent. They 

 are exceedingly brittle, the arms generally breaking off at the base, 

 w^here there is a non-muscular articulation between the first and 

 second adambulacrals and the upper part of the second and third 

 ambulacrals (not in the genus Freyella) . It is therefore very difficult 

 to get complete specimens, and often all the arms break off and the 

 small disk, which looks like a small ring when seen from the oral 

 side, is found isolated in the trawl. Some species have the habit 

 of folding their arms together against the oral side, when coming 

 unhurt to the surface, like a splendid flower closing itself up. 



Division by autotomy occurs in an Australian species, other- 

 wise the development is unknown. 



Three genera are represented in the British seas, but two 

 more may well be expected to occur there also, viz. Coljmster 

 Sladen, the single species (and only specimen) knowTi, Colpaster 

 scutigerula Sladen having been found S.W. of the Canaries 

 (25° 45' N., 20° 14' W., ca. 2750 m.), and Freyella Perrier, of 

 which the following five species are known from the East 

 Atlantic : Freyella spinosa Perrier (19°-42° N., 20°-23° W., 

 2320-4060 m.) ; Fr. Edwardsi Perrier (Bay of Biscay, S. of 

 Canaries, 1760 m.) ; Fr. sexradiata Perrier (Bay of Biscay, 

 Azores, 4020-4700 m.) ; Fr. recta Koehler (Azores, 3465 m.) ; 



