Helminth Fauna of the Dry Tortitgas. iSi 



broad ; breadth of body varies but little ; free segments with ova very much 

 elongated. The reproductive cloaca is near the posterior end of the pro- 

 glottis ; the vagina opens behind the cirrus pouch. The ovary is situated 

 about half-way between the cirrus pouch and the posterior end of the seg- 

 ment. The testes occupy the median axial region of the entire segment, 

 except a short space at the anterior end. The vitellaria lie along the mar- 

 gins, and also spread peripherally over the median axial region, thus obscur- 

 ing the other organs, especially in the mature segments. The uterus lies 

 along the median line, and, in one of the free segments, extended as a 

 slender tube containing ova, at least as far forward as the anterior third. 

 In others the ova lay in an elongated mass from just in front of the repro- 

 ductive cloaca to about the anterior fifth. 



The lateral vessels are very conspicuous, except in the free segments, 

 also the last segment in the strobiles examined did not have as conspicuous 

 lateral vessels as the preceding segments. 



Living specimens not seen. 



Dimensions, in millimeters : Length of longest about 30 ; length of head 

 and neck 1.12; head, length 0.45, breadth 0.40; bothrium, length 0.45, 

 breadth (estimated) 0.40; breadth of neck, anterior 0.24, base 0.27; bulbs, 

 length 0.32, breadth o.n ; breadth of body near neck 0.16; distance to first 

 distinct segment 0.3; first segment, length 0.03, breadth 0.16; a middle seg- 

 ment, length 1.20, breadth 0.19; last segment, length 3.68, breadth 0.32; 

 proboscis, length (estimated) I, diameter, behind and in front of bulbous 

 enlargement, 0.04, at bulbous enlargement 0.06. In a strobile 18 mm. long, 

 the last segment was 2.24 long and 0.4 broad ; the last segment in another 

 of 26 mm. in length was 4 mm. long and 0.3 mm. broad. A free segment 

 measured 5.5 in length and 0.6 in breadth. 



Mature segments resembling these have been noticed before in the chyle 

 of the spiral valve of the tiger-shark at Woods Hole, but this is the first time 

 I have seen the scoleces. 



From spiral valve of tiger-shark (Galeoccrdo tigrinus), captured June 2. 

 Eighty-five specimens were collected, all filiform, with a conspicuous enlarge- 

 ment at the base of the proboscides and edges of the bothria folded as if 

 rather thin and flexible. 



For remarks on the identification of the host see under Thysanocephalum 



(pp. 164, 167). 



23. Rhynchobothrium binuncum sp. nov. 



(Plate 8, figs. 55-64.) 



Strobile small, slender, with few segments. Bothria short, rather widely 

 separated in front, at least when compressed ; neck relatively long, with very 

 long, slender, contractile bulbs, equaling in length half the total length of 

 the head and neck ; sheaths in loose spirals ; proboscides long and for the 

 most part with small, slender spines, but with a few larger spines near the 



