812 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [94] 



The ova when highly magnified are seen to be oval and measure 

 about .OGG ram and .055 Inm in the two diameters. Each ovum contained 

 about a half a dozen globular masses, which are densely granular, stain 

 deeply, and measure about .019 mm in diameter. 



22. Calliobothrium esckrichtii Van Beneden. 



[Plate vii, Figs. 5-12.] 



Acanthobothrium eschriclilii Van Beueden, Bull. Acad., Belgique, xvi, n 



280. 

 Onchoboilmum (Calliobothrium') elegans, Diesiug, Sitz., der kais. Akad., 



xin, 585. 

 Calliobothrium eschrichtii Van Beneden, Me"m. Acad. Belgique, XXV, 142 



and 193, Plate xiv ; Diesing Re vis. Ceph., Ab. Par. 280. 



I have found a Calliobothrium repeatedly in Mustelus canis, which in 

 most particulars agrees with Van Beuedeu's G. eschrichtii from Muste- 

 lus vulgaris. Van Beneden's description of this species is thus epitom- 

 ized by Diesing : 



Head subangnlar, bothria four, angular, subelliptical, each divided into three un- 

 equal loculi by two transverse costse, armed in front by four simple subequal hook- 

 lets, and provided in front of booklets with a supplemental disk (auxiliary acctabn- 

 lum), which is sometimes simple, trilocnlar. Neck short. Anterior segments of the 

 body subquadrate, subsequently longer than broad. Genital apertures marginal. 

 Length 4 to 6 mm . 



I find in my notes records of eight different captures of this species, 

 each time in the spiral valve of the smooth dog-fish (Mustelus canis). 

 All the captures were made at Wood's Holl, Massachusetts. 



Following is a summary of the records : 



These specimens were almost invariably associated with C. verticilla- 

 turn, Rhynchbothrium bulbifer, and R. tumidulum. The same host was 

 examined on twelve other occasions in the latter part of July and fore 

 part of August without finding this parasite. 



The length of the specimens which I have obtained varies from 5 to 

 14 mm . The average of nine specimens from the capture of July 22, 1886, 

 is 9.56 mm , maximum, 14 mm ; minimum, 6 mm . 



