Mr. W. Thompson's Additions to the Fauna of Ireland. 355 



the centre of the body are prettily ramified hke those of the genus 

 Glossiphonia , as represented by Moquin-Tandon (Monog. Hirudi- 

 nees, pi. 14, 2nd edit.). Outside this central distribution of vessels, 

 the body to very near the margin is most minutely and beautifully 

 ramified all over : — the whole worm presenting the appearance of 

 a Glossiphonia "set" — in jewellers' language — in the centre of a 

 Planaria, which broadly expands on every side. This appearance is 

 literally " shadowed forth," in Sir J. Dalyell's figure 2. The colour 

 of one of mv specimens which lived in a phial of sea- water, changed 

 about once in thirty-six hours, for twelve days, was during the time 

 transparent, with the central Glossiphonia- like vessels whitish; the 

 ramifications outside them reddish lilac. 



The motion of these Planaria is " very rapid, smooth, continuous 

 and even," as Dr. Johnston describes that of the Plan, subauriculata 

 to be (Loudon's Mag. Nat. Hist. ix. 16. f. 2), and with which spe- 

 cies I cannot but consider the P. flexilis identical. The differences 

 set forth in Dr. .lohnslon's diagnostic characters of the two, are, that 

 the body of P. Jlexilis is " semicircular in front," that of the other 

 "obtuse ;" and, that the intervening sjjace between the eyes is like 

 the rest of the body in P. flexilis, but, that " a clear circular spot to 

 each of the two clusters of eyes " exists in P. subauriculata. The 

 individuals examined by me are occasionally obtuse, and occasionally 

 semicircular in front, and present themselves exactly of the forms 

 represented by both authors, as well as in innumerable other shaj)es. 

 The position of the eyes is the same in both the supposed species ; 

 the " clear circular spot " to each cluster may either have escaped 

 being recorded by Sir J. Dalyell, or possibly may not have existed 

 in his specimens ; — mine have both clusters of eyes within one trans- 

 parent circle. On full consideration of the descrii)tions and figures 

 of P. flexilis, Dalyell, and P. subauriculata, Johnston, I cannot — 

 although it is opposing my ignorance to Dr. Johnston's knowledge 

 of the subject — believe the species to be distinct. My specimens 

 agree about equally well with both species*. Further, it may be 

 remarked that my specimens have presented the form of Polycelis 

 pallidus, Quatrefages (Ann. Sci. Nat. tome iv. pi. 3. f. 8 — 1845), to 

 which they seem nearly allied : the eyes are just as represented in 

 the highly magnified fig. 9 of that species. It was obtained by 

 M. Quatrefages on many parts of the coast of Sicily. The P. flexilis 

 was procured in the Firth of Forth, and P. subauriculata in Berwick 

 bay. 



2. Euphrosina foliosa, Aud. & Edw. Hist. Nat. du Littoral de la 

 France (Annelides), p. 126. pi. 9. f. 1-4. 



Aug. 26, 1844. A very handsome Aphrodite-looking species f, 



* Having written my friend Dr. Johnston on this subject and requested 

 his opinion, he replied : — " On a re-examination of the two Planarice I find 

 the distinction attempted to be made between them too fine and uncertain, 

 so that I am forced to agree with you in the propriety of uniting them in 

 one species." 



\ It is not however of the family Aphrodis'iens, but of the Ainphinoiniens 



23* 



