[125] NOTES ON ENTOZOA O'F MARINE FISHES. 843 



median part of the segment and were much collapsed. They measured 

 about 0.05 miu and 0.025 111 " 1 in their two diameters. 



On September 6, 1887, I obtained a large, free proglottis from this 

 same species of skate (Raia erinacea) which belongs undoubtedly to 

 this Rhynchobothrium, although no Rhynchobothrium scolex was found. 

 The proglottis was l mm broad and 3.5 Ium long. Ova were observed 

 making their escape from the compressed segment in glycerine at the 

 genital aperture near one of the margins. They are collapsed and 

 measure 0.055 and 0.027 mm in their two diameters. Longitudinal strite 

 appear which converge at the two ends to a small circular hilum, which 

 marks the former point of attachment to adjoining segments. 



This species is evidently near Van Beneden's Tetrarhynchus erinaceus 

 from Raia rubus, which it closely resembles in the character of its hooks. 

 It also possesses niauy characters common to Rhynchobothrium com- 

 mutatum Dies., and It. ambiguum Dies. 



34. Rhynchobothriiim tcageneri, sp. nov. 

 [Plate xii, Figs. 10-12.] 



Bothria two, lateral, orbicular, or, in alcoholic specimens, broadly 

 elliptical, emarginate on posterior edge, somewhat bilocular, converg- 

 ing in front, widely divergent behind, with smooth, thickened, and ele- 

 vated edges. Proboscides four, in two pairs, a pair issuing from an- 

 terior part of each bothrium. Inner side of base of each proboscis with 

 a prominent shoulder, and with a single large, recurved hook on outer 

 side opposite the shoulder; base of proboscis covered with small, slender 

 hooks, remainder of proboscis armed with larger hooks. Proboscides 

 three or four times as long as bothria, tapering gradually to apex. Neck 

 long, cylindrical, broader than the body, very contractile in front of 

 bulbs ; proboscis sheaths in loose spirals ; contractile bulbs very long, 

 parallel. Body crossed by a narrow, transverse, crimson baud immedi- 

 ately behind the contractile bulbs. The segments begin almost imme- 

 diately behind the contractile bulbs. The first three or four distinct 

 segments are broader than long. The next are squarish. At about 

 the tenth they begin to elongate and mature. They increase rapidly 

 in length towards the posterior end, the median ones becoming bacilli- 

 form while the last one is, in some cases, eight or ten times as long as 

 broad. The last two or three are usually very long, fusiform, of an 

 ivory-white color, and discharge ova when placed in water. The body 

 throughout is almost cylindrical. Genital apertures marginal near 

 middleof segment. Ova spheroidal, 0.029 U1IU in diameter. Length, 18 mm . 



Habitat. Trygon centrura, spiral valve, about ninety specimens from 

 two rays, Wood's Holl, Massachusetts, August 10, 1887. 



