832 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [114] 



these objects. An examination of the alcoholic specimens has resulted 

 in finding several of these embryos clinging by their spines to the pro- 

 boscides and other parts. 



Thin longitudinal sections were made of a mature segment, the ante- 

 rior half and more of whose interior was dark colored from the pres- 

 ence of ova. The sections show that the anterior part of the segment 

 is a veritable egg-sac. Instead of ova with definite outlines, however, 

 it seems to contain nothing but a mass of collapsed egg-shells or cases 

 of a yellowish-brown color. In two or three cases I was able to make 

 out irregular conical outlines which agree in shape and size to the free 

 embryos. I saw nothing which I could certainly identify as embryos. 



Anatomy of mature segments. — My investigations on the anatomy of 

 the posterior segments have as yet been rather unsatisfactory. The 

 cirrus, which was not seen everted, appears to be short and smooth, and 

 in one instance was about .03 mm in diameter. The cirrus bulb is oval 

 aud lies nearly at right angles to the axis of the segment. In segments 

 which do not contain ova the ovaries cau be seen at the posterior end 

 as comparatively small paired organs, while the remainder of the inte- 

 rior of the segment, except so much as is occupied by the cirrus bulb, 

 is filled with oblong testicular bodies, which lie close together, at right 

 angles to the axis of the segment and in two longitudinal rows, one on 

 each side of the median line. These are separated from the marginal 

 walls by a row of smaller, roundish granular masses. In the stained 

 sections which I have thus far prepared there are but few traces of tubu- 

 lar organs or ducts. A rather large convoluted mass lies in front of 

 the ovaries which may represeut the vas deferens. A tubular vessel, 

 somewhat folded or sinuous, could be seen leading from the vicinity of 

 the ovary forwards along the median Hue. I infer from the disposition 

 of such parts as I can make out that the vagina opens marginally be- 

 side the cirrus. In front of the cirrus a space along the median line 

 becomes modified into a capacious uterus with, at first, sacculated walls, 

 but which ultimately comes to occupy all the anterior two-thirds of the 

 segment. 



The following dimensions of proboscides and hooks may be of assist, 

 ance in future identifications : 



Diameter of proboscis, exclusive of hooks 



Length of hooks 



Distance between spirals 



Number of hooks visible in one spiral 



Base. 



Middle. 



mm. 



mm. 



0.022 



0.019 



0.006 



0.008 



0.008 



0.014 



12 



12 



This species seems to be near R. rubromaeulatum Dies. (Tetrarhyn- 

 chus Trygonis pastinacecv Wagener.) 



