[23] ENTOZOA OF MARINE FISHES OF NEW ENGLAND. 475 



botliria are reflexed. Xeek flattened, rather slender, increasing uni- 

 formly backwards and merging imperceptibly into the jointed body, 

 covered, sometimes sparsely, sometimes thickly, with very small, 

 straight, sharp, bristle-like spines. The body has at first an unbroken 

 outline, the square segments being indicated simply by fine, transverse 

 lines. Farther back the segments become elongated, with the corners 

 slightly rounded. Genital apertures marginal, opeuiug about the mid- 

 dle line. 



The compound hooks of the head have three recurved prongs each, 

 the middle one slightly longer than the others, the inner one the short- 

 est. These prongs rise from a common horizontal part, which is itself 

 supported by a flattened or spatnlate process, which lies immediately 

 under the middle prong, is about the same length and parallel with it. 



The following measurements were made from a mounted specimen: 



Millimeters. 



Length of strobile 40. 00 



Length of head 0.52 



Breadth of head 0.44 



Breadth of neck 0. 12 



Length of first segments, 2 mm from head 0. 03 



Breadth of first segments '. 0.01 



Length of segments, 3 mm from head 0. 20 



Breadth of segments, 3 mm from head 0. 42 



Length of segment, 6 mm from head 0.34 



Breadth of segments, 6 mm from head 0. 42 



Length of posterior segments 2. 20 



Breadth of posterior segments 0. 84 



Length of hooks 0. 10 



Length of bristly spines on neck or body 0. 01 



A few specimens in the lot differed from the prevailing type in being 

 much more irregular in outline and having in general a more fragile, 

 structure. The neck is much distorted by contraction and much 

 broader than in the prevailing type; the first segments, on the con- 

 trary, are longer and more slender. The posterior segments are ellip- 

 tical, oblong, flatter, and more fragile in appearance. 



In one specimen I found what seemed to be a transverse costa on the 

 face of a bothrium. I looked in vain for a similar characteristic in the 

 other specimens of the lot. If such costa'. could be proved to be char- 

 acteristic of this worm it would indicate a very close relationship with 

 Calliohothrium. 



. In some the bristly spines were found on the neck and not on the 

 body, in others sparsely on the body and not on the neck, in others 

 thickly on both neck and bod}'. They are, without doubt, the remnant 

 of a bristly outer covering of the body, which is characteristic of the 

 young and larval conditions of this genus. 



The genus CylindropJiorus is a provisional one made by Diesing to in- 

 clude a single species which is not well known. He, however, includes it 

 among those Tetrabothrice, which are characterized by having no auxil- 

 iary acetabula on the bothria. The presence of a well-defined auxiliary 



