706 MR. F. F. LAIDLAW ON THE POLYCLAD [June 19, 



possible to form any idea as to the characters of the Polyclad 

 fauna of the warmer waters of the Eastern part of the Atlantic. 



Its close general resemblance to the Mediterranean fauna is 

 obvious. Compared with that of the "Western Atlantic, so far as 

 this has been made known to us through the researches of Verrill 

 [1888], it need only be said that the two areas, the Cape Yerde 

 Islands on the one hand and the New England Coast on the other, 

 do not appear to have a single species in common. When con- 

 trasted with the fauna of our own coasts, it is evident that there 

 is a limit to the northward extension of many of the species 

 characteristic of the Mediterranean and warmer parts of the 

 Atlantic. Thus Prosthiostomtcm siphunculus occurs on the Jersey 

 coast, but has never been recorded from the northern shores of 

 the Channel. But at the same time our Polyclad fauna must 

 not be regarded as being merely an impoverished ' Lusitanian ' 

 type, there is some evidence that it includes also ' Boreal ' species 

 which find in British seas the southern limit of their range. For 

 example, Cryptocelides loveni has been taken in the Clyde area, but 

 has not been found further south than this (I am strongly inclined 

 to believe that the locality given for a specimen in the British 

 Museiim, namely Port Phillip, is a mistake). 



So that it will, I believe, in the future be possible to recognise 

 faunistic areas in the Atlantic for Turbellaria just as such areas 

 have already been delimited for Mollusca. 



The absence of any species of Pseudoceros, and the presence of 

 several members of the Eui-yleptidae in a collection containing 

 some sixteen species, at once marks a striking conti'ast with any 

 series of specimens I have had the opportunity of examining from 

 the Indian Ocean, though perhaps further collecting may serve 

 to decrease the distinction. 



ii. Notes on the Specimens in the Collection. 



Notes supplied to me by Mr. Crossland on his material are here 

 printed between inverted commas. Numbers in square brackets 

 give reference to literature. Numbers between curved brackets 

 ( ) refer to Mr, Crossland's register of specimens. 



Planocerid^, 



Planocera grafpii Lang. 



Planocera graffii Lang, Naples Monograph xi., Polycladen, 1885, 

 p. 434. 



Three specimens. (15-17.) 



"Translucent brown with sparse reticulum of darker, more 

 opaque lines. Outline very wavy during the act of crawling ; the 

 animal uses muscular action in progression and extends and 

 attaches a small part of the margin of the front of the body, then 

 hauling itself along by this. It reminds one somewhat of an 

 octopus when crawling." 



