410 



ECHINODERMS OF THE BRITISH ISLES 



Key to the species of Pseudocuciimis known fron or possibly 

 oeeurrimj in the British seas. 

 Deposits tables, with the spire formed by 4 columns 



1. Ps. inixla Ostergr. 

 Deposits tables, with the spire formed by 2 columns 



Ps. marioni Marenz. 



1. Pseudocucumis mixta Ostergren. (Fig. 247, 1-2.) 



(Syn. Pseudocucumis Cuenoti Koehler and Vaney.) 



Body elongate, cylindric, attenuated towards the ends, 

 younger specimens the tube-feet form regular double series 

 larger specimens they are more crowded in the middle part of 

 the body, forming up to 6 double series, only a narrow naked part 

 being left in the interradii. Both radialia and interradialia in 

 the calcareous ring with a long, articulate, posterior prolongation, 



In 



in 



c= 



=5S 



^=^ 



1 2 3 



Fig. 247. — Calcareous deposits from the body wall (1) and the tentacles (2) 

 of Pseudocucumis mixta ; deposits from the tentacles oi Thyonidium 

 pellucidum {S). x 100. (1. After Ostergren ; ivom Dan7nark''s Fauna.) 



bifurcating at the end. Calcareous deposits (Fig. 247, 1) very 

 numerous, lying crowded in the skin ; they are tables with a large 

 disk perforated by many holes and with smooth edge ; the spire 

 composed of 4 columns. Tentacles with numerous slender rods, 

 slightly widened at the ends (Fig. 247, 2). Colour yellowish- 

 violet ; the tentacles often darker. Grows to a size of at least 

 20 cm., probably more. 



It lives on a stony, muddy bottom, probably also on sandy 

 bottom. May be found thrown up on the beach after storms. 

 Development unknown. 



In British seas this species has been found off the Irish w^est 

 coast in depths of 32-67 m. No doubt it will be found to have 

 a wider distribution along the British coasts. It is elsewhere 



