MancJicster Memoirs, Vol. xlviii. (1903), No. 4. 15 



muscular sheath, whilst the backward prolongation of the vagina, 

 save that it appears to open to the exterior, distinctly recalls the 

 receptaculum seminis of Paraplaiiocera. 



Note D. — The genus Leptoplana as at present constituted 

 contains, as I have pointed out elsewhere (:03a), three very 

 distinct groups. The first of these includes only Z. tref?tenarts, 

 which is unfortunately the type of the genus; the second also 

 contains at present only one species, Z. subviridis. The 

 numerous remaining species form the third group which 

 agrees much more closely with other genera of the Leptoplanidae, 

 in so far as the structure of the male organs is concerned, than- 

 do either of the first two groups. 



Note E. — The " very small median vesicle " into which the 

 vasa differentia of Haploplana ellioti open (:03) is precisely 

 similar to the penis of Enantia spmifera as figured by von Graff 

 ('89). This similarity combined with a further agreement in the 

 position of the pharynx, which lies relatively much nearer the 

 anterior margin than in any other Acotylean genus, are sufficient 

 to indicate a relationship between these two genera. 



IV. Literature. 



45. QuATREFAGES, A. DE. " Memoire sur quelques Planariees 



marines." Ann. sci. fiat. (3) Zoologie, iv. 1845, PP- 



129-T84, Pl.3-7. 

 '84. Lang, A. " Die Polycladen : Fauna und Flora des Golfes 

 -^ von Neapel," xi. 1884. 



'88j Verrill, a. E. "The Marine Planarians of New England." 

 v_/ Trans. Connect. Acad, viii., pp. 459-520, PL 40-44. 



'89. Graff, L. von. " Enantia spinifera, der Reprasentant 



einer neuen Polycladen Familie." Mittli. natiirwiss. 



Ver. Steiermark. 1889. 

 '92. " Pelagische Polycladen." Zeitschr. f. Wiss. ZooL, LV. 



pp. 189-219, PI. 7-10. 1S92. 

 '93. Bergendal. " Polypostia similis n. gen. n. sp." 



