79G REPORT OF COMMISSIONER OF FISH AND FISHERIES. [78" 



var labile while in A. gracilc they are quite distinct in living specimens, 

 although it must be confessed they were found with extreme difficulty 

 in the alcoholic specimens. 



ORYGM^TOBOTHRIUM, Diesing. 



Body elongated, articulate depressed. Head separated from body by a nock, with 

 four opposite cap-shaped bothria, attached by a contractile pedicel, highly versatile, 

 and each provided with two scrobiculiform supplementary disks (auxiliary acetalmla). 

 Genital apertures marginal. (Diesing.) 



Van Beneden originally described the species 0. versatile Dies, under 

 the name Anthobothrium musteli. The species was taken out of the 

 genus Anthobothrium by Diesing on account of the two supplemental 

 disks on each of the bothria. 



The name Anthobothrium was retained by Diesing, and is used in this 

 paper, to designate those Tctrabothriidw whose bothria are unprovided 

 with auxiliary acetabula. 



With regard to the supplemental disks at the center of the bothria 

 Van Beneden says : 



Upou studying these appendages (bothria) with the aid of a compressor, other 

 characters appear which seem to be peculiar to this species* In the middle there is 

 a circular baud surrounded with fascicles of muscular fibers making a circle at the 

 center which produces the effect of a cupping disk. 



The essential generic characters of these specimens, from Carcharias, 

 are about as follows : 



Body elongated, articulate, depressed. Head separated from body by 

 a neck, with four opposite cup-shaped bothria attached by short con- 

 tractile pedicels, highly versatile, each provided with a single supple- 

 mental disk on anterior end of border. Border of bothria entire, with- 

 out loculi. Genital apertures marginal. 



In 0. crispum (Tetrabothrium (Anthobothrium,) crispnm Moliu), the 

 second of the two species which Diesiug includes in this genus, it ap- 

 pears to ine, judging from Molin's figure, that the "central nmbo" of 

 that author, while probably of the same nature as Van Beneden's "cir- 

 cular baud," is not to be regarded as a supplemental disk. 



Whatever may be the final disposition of the genus Orygmatobothri-um 

 there can be little doubt of the relationship of 0. angustum to Van 

 Beueden's Anthobothrium musteli.* 



17. Orygmatobothrium angmtu'in Lt. 



(.Plato vn, Fig. 3.] 

 Report of IT. S. Fish Commissioner for 1S8G, pp. 4G8-9, Plato in, Figs. 1-3. 



In the summer of 1S87 I obtained this parasite of the dusky shark! 

 (Carcharias obscurus) on two different occasions. I give the following ^ 



*Zschokke's admirable monograph, Rectierclies stir Structure Anat. ct Ifist. des Ces-l 

 todes (Menu. lust. nat. Geudv., Vol. xvn, 1883), which readied mo before these iiotesl 

 were published, leaves no doubt whatever about the presence of two auxiliary aceta- 

 bula on each boturium of Anthobothrium (Orygmatobotlvrium) musteli Van Ben., and of 

 Oryfjmatobothrium longicolle Zschokke 



