400 



ECHIN0DERM8 OF THE BRITISH ISLES 



holes (Fig. 238, 1) ; above this layer lie more scattered some 

 smaller, rounded plates with few holes (Fig. 238, 2), and in the 

 superficial layer again rather numerous small cup-shaped bodies 



(Fig. 238, 3). Transitional forms 

 between the tw^o kinds of plates 

 are found. Colour usually dark 

 brownish, which keeps well on 

 preservation in alcohol. Grows 

 to a length of ca. 15 cm. 



It lives on muddy bottom, 

 where it lies buried wdth only the 

 anterior and posterior ends above 

 the surface ; it has been observed 

 in aquaria to lie for long periods 

 w^ith the anterior end wholly con- 

 cealed in the ground, which might 

 indicate that it does not exclus- 

 ively subsist on plankton and 

 detritus, but may fill its ali- 

 bottom material. Development 



Fig. 238. — Calcareous deposits of 

 Cucumaria elongata. 1, x .50 ; 

 2-3, X 145. (From Danmark's 

 Fauna.) 



mentary canal directly wdth 

 unknown. 



In British seas this species is known from Plymouth, round 

 the west coasts to the Shetlands, and 

 to Northumberland and Durham on the 

 east coast, in depths of ca. 4-65 m. 

 It is elsewhere distributed from the 

 Trondhjem Fjord to the Sound in the 

 Scandinavian seas, and to Heligoland 

 in the North Sea ; further, to the 

 Mediterranean in the south. It is not 

 known from Greenland or the east coast 

 of N. America. 



Fig. 239. 



Calcareous 



deposits of Cucmnaria 

 Hyndmani (1) and Cue. 

 Jrondosa, j-oung (2). 1, 

 X 50 ; 2, X 80. (From 

 Danmark' s Fauna.) 



3. Cucumaria Hyndmani Thompson. 

 (Fig. 237, 3.) 



Body short, rather barrel-shaped, 

 slightly attenuating posteriorly, slightly 

 curved. Skin thick, smooth, leathery. 

 Tube-feet almost completely retractile, in distinct double rows. 

 Deposits (Fig. 239, 1) large, smooth, fenestrate plates, lying very 

 close and, when the animal is contracted, imbricating like scales. 

 Colour whitish -grey or faintly reddish. Grows to a length of 

 ca. 5 cm. 



