A. E. Vet-rill — Marine Planarians of Neio England. 511 



rior. The superficia^l nerves are extensively anastomosed, so as to 

 form a network of irregular meshes. 



Ovaries lai'ge, on each side of the digestive cavity; oviducts large, 

 often much distended posteriorly by clusters of large mature ova. 

 Spermarian folicles numerous, situated on each side of, and often 

 extending nearly or quite around, the digestive cavity. Vasa de- 

 ferentia large, more or less saccular posteriorly, when distended 

 with their contents, and connected with a circular seminal vesicle 

 surrounding the base of the penis. 



The penis is unarmed and in contraction ovoid or conical, but 

 rather long, tapered, and usually somewhat curved when fully ex- 

 tended. (See plate xliv, figs, 6, 8, 9). 



The male orifice is near the posterior margin, in front of the 

 median caudal cirrus. 



The female orifice is situated a little farther forward and com- 

 municates with a simple tubular vagina, which runs up dorsally 

 beneath the saccular spermatheca. 



Spermatheca or bursa serninalis is large, complex, reniform or 

 cordate, with numerous chitinous outlet-tubes scattered over the 

 surface. 



Rhabdites and pigment-corpuscles are contained in the integument. 



Polychcerus caudatus Mark. 



Mark, op. eit., pp. 298-309, pi. xxi, figs. 1-22, anatomy. 



PL.'ITE XLI, figures 11, 11a; PLATE XLIV, FIGURES 6 TO 10. 



Body depressed, flat or concave beneath, somewhat convex above, 

 and often gibbous or swollen dorsally, when filled with ova ; in 

 extension varying from broad cordate to narrow-ovate, according 

 to the state of contraction ; front end bluntly pointed or evenly 

 rounded ; sides often nearly parallel ; posterior end usually deeply 

 emarginate, with a broad median notch and rounded lobes each side 

 of it ; margin thin, sometimes inflexed, especially when swimming. 



Caudal cirri one to five. In adult examples there are generally 

 three slender, pale, translucent caudal cirri, one of which is median, 

 while the others, which are usually a little smaller, arise from near 

 the inner border of the posterior lobes. Sometimes, in large speci- 

 mens, another smaller pair is developed external to the latter, on 

 the posterior lobes (pi. xliv, fig. 6). In young specimens the 

 median cirrus appears first. The cirri all arise at a slight distance 

 from the margin, on the dorsal side. Each one can be retracted 

 into a small, basal, bulb-like, muscular, invaginated cavity of the 



