55] NOTES ON ENTOZOA OF MARINE FISHES. 773 



jength, 25.55; length of bothrium at rest, .7; breadth, .53; breadth 

 f head, 1.23; breadth of first segments, about 1 back of head,l ; length, 

 3; breadth of median segments, .72; length, .15; average length of 

 losterior segments, .13 ; breadth, .8. 



In the above specimen there was a constriction behind the head .28'"'" 

 n diameter, while immediately behind the constriction the neck was 

 16 1 "" 1 in diameter. Near the posterior end of the strobile there was an 

 nlargenieut due to contraction, which was l.l miu in diameter. In au- 

 ither specimen, 20" im in length, the first segment began less than l mm 

 roin the head, where they were .8 mm broad and .05""" long. The median 

 egments were lA mm broad and .l mm long. The posterior segments 

 eere narrower, breadth, .44 mm , length, .4G U1U1 , with rounded angles, 

 he strobile here being somewhat moniliform. 



The vessels of the water- vascular system were quite evident in the 

 iving specimens, both in the body and the bothria. One set of longi- 

 udiual vessels, consisting of a single vessel near each margin, was pe- 

 uliar in that each vessel was quite irregular, swelling out into suboval 

 nlargements and giving off short lateral branches at intervals. These 

 nay be nervous vessels. 



When the specimens were placed in alcohol the longest of the three 

 ontracted until it was shorter than the others. 



Anatomy of the segments and bothria. A few of the posterior segments 

 f one specimen were stained with carmine and cut into longitudinal sec- 

 ions. The segments all proved to be immature, and consequently only. 

 b comparatively few points in their anatomy could be made out. 



The outer coat of the muscular wall is composed of two layers of 

 inely fibrous tissue, an outer layer of circular, and an irmer of longitu- 

 al fibers. In sections these two sorts cross each other at right aii- 

 ?les, forming a net-work with rectangular meshes. Beneath the outer 

 ibrous layers is a thick layer of densely granular tissue. The granules 

 tain deeply with carmine, and are from .003 to .OOG nnn in diameter. 

 Beneath the granular layer is a layer of longitudinal muscle fibers, 

 ihese are larger than the fibers in the outer longitudinal layer, and 

 ire arranged in straight, parallel fascicles, which are from .0025 to 

 005 1 " 1 " broad and .0025'"'" apart, 



The most prominent organ in these segments is the cirrus and its 

 jheath. In all cases the former was retracted. The external opening 

 3f the cirrus is at the margin near the anterior edge of the segment. 

 ' Che sheath, with the inverted cirrus, extends a little past the middle 

 ine of the segment. The cirrus when extruded must be therefore rela- 

 tively quite long. The sheath enlarges towards the center of the seg- 

 nent, where its diameter nearly equals the length of the segment. 

 The length of one was .28 mm ; its diameter at base .027""". The cirrus 

 toroughout all its length is thickly beset with spines. The spines at 

 ;hebase are much longer and stouter than those along the middle and 

 at the apex. Some of the basal spines were .008 mm in length, and .003 U1IU 



