FAUXA OF THE OUTER WESTERN AFvEA OF THE CHANNEL. 299 



Dentaliicm cntalis was not found outside the 18-mile point. 



Nucula nucleus, which occurs commonly down to 30 fathoms on the 

 Eddystone Grounds, was only obtained at the first position, 8 miles 

 distant, where the large deposit of fine clean sand occurs. 



Pcctunculus gbjcimeris, occurring as far as 39 miles out, was remark- 

 able for the small size of specimens obtained. 



Cardium ecJdnatum was of rare occurrence, being only once obtained 

 alive at 9 miles distant, while only one dead valve was recorded at a 

 point slightly closer in. 



Cardium norvegicum, common on gravel on the Eddystone G-rounds, 

 was only recorded at four points, and as far as 31 miles. 



(2) Of the members of the Plymouth fauna that are absent from the 

 list, there is little of special interest to mention, these being for the 

 most part essentially littoral species, or those favouring a rocky habitat, 

 or such as are of too infrequent occurrence generally to serve for purposes 

 of comparison. Among the absent species : — 



Adamsia pohjjncs {Sagartia ixirasitica) was conspicuously absent 

 despite the frequent occurrence of its host Ewpagurus hcrnhardus. On 

 the Eddystone to Start Point G-rounds, it is an interesting fact that 

 on gravels Dr. Allen always found this hermit-crab without the 

 anemone, though on the fine sands it was commonly associated with it. 

 It is true the anemone did not occur in the few hauls made on the fine 

 sand of the outer area at about 8 miles, yet its non-occurrence in other 

 hauls suggests that the generally coarse ground of the latter, as in the 

 case of the Eddystone to Start Point gravels, may account for its 

 absence. 



Holothuria nigra is generally found at Plymouth in close proximity to 

 rock ledges. Such too was the case in the Eddystone to Start Point 

 fauna where the species occurred only on gravel adjoining the Eddy- 

 stone rocks. It is not improbable that such rock ledges are still 

 exposed in places on the more distant grounds here dealt with, but 

 there was no clear evidence of this fact afforded by the rock material 

 dredged up at any point. 



Antedon bifida, which extends southward to the Mediterranean, and 

 as deep as 100 fathoms (cf. Bell, 65), has not been recorded in the 

 Plymouth fauna outside the Mewstone Ledge. 



JEchinocardium cordatum occurs on fine sand on the Eddystone 

 Grounds to 35 fathoms, and was obtained occasionally by Dr. Allen on 

 similar ground between the Eddystone and Start Point. It is recorded 

 by Ludwig (72) from southern waters at Marseilles, Naples, and the 

 west coast of Italy, and as deep as 85 fathoms. 



Maia sqiunado is moderately common, especially among rocks in the 



