668 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



like that of Hwmopis ; internal reproductive organs similar to those of 

 Hiriido ; while the external male organ is more like that of Hmmopis. 

 The genus differs from all the others, however, in the situation of the 

 genital orifices, in the form of the maxilliB, the number of plications in 

 the OBSoifhagus, &c. It includes one of the stoutest, largest, and most 

 powerful of the leeches hitherto described. 



Macrobdella DECORA Verrill. 



Araericaa Journal of Science, vol. iii, p. 133, fig. 4, February, 1872. 

 Hlrudo decora Say, Long's Second Expedition, vol. ii, p. 268, 1824; Diesing, Sys- 

 teiua Helm., i, p. 474; Leidy, Proc. Phil. Acad. Nat. Sci., 1868, p. 230. 



Body large, stout, broad, considerably dei)ressed throughout ; in exten- 

 sion much elongated, and gradually tapering anteriorly; strongly annu- 

 lated. Length of the larger specimens twelve inches or more ; greatest 

 breadth upward of an inch. Head rounded in front, the cephalic lobe 

 capable of considerable dilation, consisting, apparently, of five segments. 

 Ocelli, 10 : the first pair between the second and third segments ; the 

 second on the third; the third on the fourth; the fourth pair on the 

 sixth, or buccal; and the fifth on the ninth segment, or fourth behind 

 the mouth. Cephalic lobe rugose and wrinkled beneath, and with con- 

 spicuous longitudinal sulcations, of which three, corresponding with the 

 maxillas, are deepest; posteriorly with a conspicuous semicircular fold, 

 surrounding and partially concealing the maxillie when retracted into 

 their fossae. Maxilloe thick, very prominent, higher than broad ; outer 

 edge rounded in front, and finely and closely denticulate. Below each 

 maxilla, in the Oisophagus, is a broad plication or fold, which often 

 divides into two a short distance beyond ; alternating with these are 

 three simple narrower folds, making six or nine in all. External male 

 organ prominent, stout, conical ; the broad wrinkled base rising from the 

 twenty-fourth to the thirtieth segments; the terminal portion smoother, 

 with six sulcations ; the orifice small, with six lobes, opening in the 

 twenty-sev'enth segment. Female orifice also with small lobes, sur- 

 rounded by a slightly elevated area, formed upon the thirty-first and 

 thirty-second segments: posterior to these, there are four conspicuous 

 rugose elevations in a quadrangle on the thirty-sixth to the thirty-eighth 

 segment, and smaller ones on the thirty-ninth segment, with less marked 

 ones on two or three of the previous and following segments; corre- 

 sponding to these rugosities, there are well dev^eloped internal glands. 



The reproductive organs are here described from preserved specimens, 

 of large size, taken in the breeding season, in spring. At other seasons, 

 and in smaller specimens, these characters are not so obvious. Acetab- 

 ulum large, separated from the body by a well marked constriction. 



Color above, dark livid brown, or olive-green, with a median dorsal 

 row of about 20 to 22 bright or pale red spots, which are sometimes 

 obsolete, and a row of rounded black spots near each margin, corre- 

 spondiug in number, and nearly in size, with the red ones. Lower sur- 



