[115] NOTES ON ENTOZOA OF MARINE FISHES. 



29. Rhynchobothrium hispidum, sp. nov. 

 [Plate xi, Figs. 12-17.] 



Bothriatwo, lateral, entire, subelliptical, edges elevated, face hollowed 

 out to form a cupping-disk, widely separated posteriorly, somewhat 

 approximate anteriorly. Keck relatively long, wider than first seg- 

 ments, sub-cylindrical, very contractile, with two small crimson spots 

 immediately in front of the contractile bulbs; when highly magnified 

 seen to be densely covered with minute short bristles. Proboscides 

 very long, slender, armed with hooks of two principal sorts, one sort 

 short, sharply recurved and very broad at the base, the other sort slen- 

 der and arcuate, but stouter than those of R. tenuispinc, and not so close 

 together. First two segments short, squarish, indistinct, broader than 

 long, third segment about as long as the first two, fourth segment about 

 as long as the second and third, remaining segment increasing in 

 length, last segment very much longer than broad. Whole number of 

 segments about six. Posterior segments separating easily, usually very 

 long and slender and somewhat fusiform. Genital apertures, male 

 marginal, about .posterior third. Length from 4 to 8 Ium . 



Habitat Trygon centrura, spiral valve, July and August. Wood's 

 Holl, Massachusetts. 



At different times during the past two summers I have found some 

 exceedingly small Rhynchobothria in the spiral valve of the sting-ray 

 (Trygon centrura), the most of which were characterized by having two 

 small red spots in the substance of the neck in front of the contractile 

 bulbs. It has so happened that I have obtained several other more 

 conspicuous forms at the same time, so that these smaller forms have 

 never been studied carefully while living. Upon examining the alco- 

 holic specimens I find it necessary to separate these small Rhynchoboth- 

 ria into three distinct species on account of the profound difference in 

 the style of hooks. These species bear a close resemblance to Van 

 Beneden's TetrarJiynchus minutus from Squatina angelus, but differ from it 

 in having the crimson spots in the neck. Van Beneden, furthermore, 

 represents his species as having the bothria profoundly bilobed and the 

 hooks, according to his figure, of uniform size. The species R. tenuispine 

 resembles R. heteromerum Dies, in some particulars. The resemblances 

 and differences are mentioned under the description of R. tenuispine. 



R. longispine may prove to be a variety of R. hispidum. 



I have found R. hispidum on three different occasions as follows: 



H. Mis. 133 53 



