458 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



Millimeters. 



Breadth of head in front, widest part 0. 90 



Breadth of head just behind the front rim 0.80 



Breadth of marginal lobe, about the middle 0.90 



Breadth of head, narrowest part 0. '21 



Breadth of first segment, widest (posterior) part 0. 80 



Breadth of first segment, narrowest (anterior) part 0.42 



Length of longer alternate segments, first series , 0.40 



Length of shorter alternate segments, first series 0. 24 



The segments of the first series are sometimes notched or crennlated 

 on the posterodateral margin, with a single median indentation ; in 

 others the edge is but slightly waving ; in others it is nearly entire. 



The following measurements are from a young specimen : 



Millimeters. 



Length of strobile 20.00 



Length of head 2.10 



Breadth of head, anterior 0. 80 



Breadth of head j list back of anterior rim „ 0. 60 



Breadth of head, narrowest (constricted) part 0,31 



Breadth of first segments, widest (posterior) part 0. 50 



Breadth of first segments, narrowest (anterior) part 0. 28 



Average length of segments, longer alternates 0. 35 



Average length of segments, shorter alternates 0. 24 



Breadth of widest segments 0. 90 



Average length of widest segments 0. 12 



Width of posterior segments 0. 35 



Length of posterior segments 0. 30 



Habitat. — Both young and adult, one specimen of the former and six 

 of the latter, were taken from the intestine of a spear- fish (Tetrapturw 

 aibidus Poey), August 8, 1885, at Wood's Uoll, Mass. 



Dibotlirium aluterw, sp. now 



[Plate I, Figs. 5-8.] 



Near Dibotlirium microcephalum Rudolphi, Diesing, Systenm Helminth., i, 592. 



Ibid., Sitzungsb., xiii, 578, Revis. Ceph., Par. 241. Wagener, Nov. Act. 



Nat. Cur., xxiv, Suppl., 16, 69, tab. vn, 77. Van Beneden, in Bullet. 



Acad. Belgique, xxii, ii, 521. 

 Bothrioccphalus microcephalus Bellingham, Ann. Nat. Hist., xiv, 253. (Habitat, 



Orihayoriscus mola. ) 



Head subsagittate with rounded apex ; bothria oblong, lateral ; neck, 

 none; first joints distinct, about as long as wide, becoming much shorter 

 and crowded together, much wider than long; genital apertures un- 

 known. 



Habitat. — File Fish (Alutera Schcepfii), Wood's Holl, Mass., August, 

 1SS1 ; 101 specimens from intestines of a single fish. 



These specimens were all immature, none of them had the genital 

 apertures developed. They ranged in length from 20 mm to 91 m,u . The 

 bothria in the smaller specimens are convex (Fig. 5), the central con. 

 vex portions thin and transparent. A lateral view shows the bothria 



