550 PROCEEDINGS OF THE NATIONAL MUSEUM. vouxxl 



PLACOBDELLA R. Blanchard. 



6. PLACOBDELLA MEXICANA, new species. 



H'latft XL, fig, 3.) 



This species is close to Placohdella plana (Wliitinan) It. Blaucbard, 

 but tlie aiinulatiou difleis in several respects. The body is broad and 

 depressed, aud rather ovoid in outline. The largest specimen measures 

 14.7 mm. in length and C mm. in breadth at the widest part. The ace- 

 tabulum is small and weak, and about 2.5 mm. in diameter. 



The prostomium is undivided. It is followed by a rather wide ring, 

 which bears the single pair of eyes on its posterior part, and the first 

 pair of dorso-inner-lateral papilla on its anterior part. A plain nar- 

 row ring follows, then abroad double one bearing the second ])air of 

 dorso-inner-lateral papilhe on its anterior half. A narrow ring com- 

 pletes with this doul>le one somite III. Somite IV is in one specimen 

 similarly constituted of a broad double ring and a narrow one; in the 

 others it is constructed like the following somites of three rings, the 

 first of which bears papilhe. Somite XXII is the last complete one; 

 XXIII has two annuli, XXIV a single annulus, double at the margin, 

 and XXV and XXVI each a single papillate annulus. The male pore 

 is situated between the twenty-fourth and twenty-fifth, the female pore 

 between the twenty-sixth and twenty-seventh, and the anus between 

 the sixty sixth and sixty-seventh annuli. 



The dorso-median and dorso-inner-lateral jiapilla; are large and con- 

 spicuous, but low, smooth, and rounded. The former begin on annulus 

 eight (somite V) and continue with the latter to somite XXVI. The 

 outer lateral are small; they begin on annulus eleven, the first of somite 

 VI, and continue to annulus fifty-nine (somite XXIIj. The second 

 annulus also of ^ch somite of the middle region of the body bears 

 six series of small papilla which lie mesiad to the corresponding ones 

 of the first annulus. 



The color of the alcoholic specimens is a rich chocolate brown V^lotched 

 ■with lighter and darker brown, a branched figure of the latter color 

 corresponding very closely with the branches of the intestine, and the 

 pale spots in general with the papilhe. A median white line appears 

 at the anterior and posterior ends of the body. Beginning anteriorly 

 in a triangular area which incrludes the eyes, it is more or less inter- 

 rupted and broken at the first annulus of each somite to the seventh, 

 where the band fades out. On the second annulus of each of these som- 

 ites the pale area runs out laterad in transverse bars, which on V reach 

 nearly to the margins of the body. At the posterior end a similar nar- 

 row pale area extends forward from the anus to somite X XI. Marginal 

 white spots occur metamerically on each somite. The posterior sucker 

 is marked with alternating rays of brown and white, the latter being 

 confined mainly to the marginal half. 



Typex.—So. 5028, U.S.X.M. Mexico; P. G, Jouy; Xo. 384. Three 

 specimens. 



