HOLOTHURIOIDEA 435 



summer-time (in the Mediterranean apparently almost through- 

 out the year). 



The variety profundicola Kemp is stated to differ from the 

 typical digitata in the anchor plates, which are " far more irregular 

 and of a lighter build. They are roughly triangular in shape, 

 with six large primary holes, three at the base near the handle, 

 two larger ones in the middle, and a single one at the apex. . . . 

 The primary perforations are often completely or incompletely 

 divided by a narrow bar." Colour deep purple.^ 



In British seas Labidoplax digitata appears to be distributed 

 all around the western coasts, from Plymouth to the Shetlands, 

 whereas it does not appear to be found on the east coasts. It 

 is otherwise known from the Atlantic coasts of France and the 

 Mediterranean. Bathymetrical distribution from within tide 

 limits to ca. 70 m. The variety profundicola is recorded from off 

 W. Ireland, from 66-268 m. 



3. Labidoplax Thomsoni (Herapath). (Fig. 267.) 



(Syn. Synapta digitata, var. Thomsoni Herapath.) 



In general aspect like the preceding species, but differs from 

 it in lacking the groups of sensory organs on the inside of the 

 tentacles. In the internal anatomy it is not known to differ from 

 the preceding species. ^ The calcareous deposits offer the main 

 distinguishing characters of the species (Fig. 267). They are 

 markedly different in the anterior and posterior ends of the body. 

 In the anterior end the anchor plates are rounded, with serrate 

 edge, and consist of a complicated, thick, irregular network, not 

 a simple fiat plate as otherwise usual in Synaptids ; they are 

 opaque, almost black, only the very short handle being of the 

 usual transparency. They are usually ca. 0-15 mm. long. The 

 anchors are short, with arms very divergent. Towards the 

 posterior end of the body the plates gradually become thinner, 

 the thick, secondary network disappearing ; these plates are 



1 As no figures are given of the calcareous deposits of this form, and as, 

 moreover, the figures given in Bell's Catalogue (PI. I. 3) as representing the 

 calcareous bodies of L. digitata (which have served for comparison) are 

 partly (viz. the two figures with serrate holes) not of this species, but of 

 L. Buski, it is very difficult to form a definite opinion of the value of this 

 variety profundicola (Stanley W. Kemp, " The Marine Fauna of West 

 Ireland", iii., Ann. Rep. Fish. {Ireland), 1902-3, Part II., App. VI. (1905), 

 p. 184). 



2 The author has not had the opportunity of examining specimens of 

 this species. 



