12 SIXTEENTH REPORT. 



mcnt of materials, measures 1.5-1.6 mm. wide and the three small pieces 

 about 1.75 mm. wide. 



Head. The head (PI. 1. fig. 2) which was somewhat twisted is globose 

 with a rounded apex. It is flattened dorsoventrally, 0.342 mm. broad, 

 slightly broader than the neck. Its length to the posterior margin of the 

 suckers is 0.252 mm. and to the constriction of the bullions end 0.324 mm. 

 There are no furrows nor rostellum present, nor are there any hooklets or 

 spinelets of an 3^ kind. 



Suckers. The four suckers borne on the broadest part of the head are 

 shallow, oval in outline, prominent and of large size. A functional fifth 

 sucker is lacking and on account of the scarcity of material the head could 

 not be sectioned and examined for the presence of a vestigial fifth sucker. 

 The four suckers measure over all 0.18 mm. long bv 0.126 mm. broad, 0.18 

 by 0.108, 0.198 by 0.126, 0.162 by 0.09 mm. average 0.18 by 0.11 mm. The 

 measurement of breadth of the last sucker is probably too little on account 

 of foreshortening. 



Neck. The neck is thin, flattened and slightly narrower than the head, is 

 somewhat swollen for a short distance, then is sharply contracted. Its 

 maximum breadth, 0.324 mm., is found 0.9 mm. posterior to the tip of the 

 head and its minimum breadth of 0.231 mm. about 1.26 mm. from the tip 

 of the head. Its length to the first visible signs of internal segmentation 

 (stained slide) is 3.2 mm. The first outward signs of segmentation appear 

 4 mm. from the tip of the head. 



Segmentation. Segmentation is not evident in young or in nearly mature 

 proglottids but is more evident in fully mature proglottids and is readily 

 seen in fulty ripe proglottids. For the most part the margins of the strobila 

 are smooth. The limits of the individual ripe proglottids are marked by 

 slight indentations at the corners and these indentations are connected by mi- 

 nute transverse furrows. The surface of the worm is more or less wrinkled. 

 The color in the preserved worm is white. The cuticula is smooth, there 

 being no spines or hooklets of any kind. 



Proglottids. All proglottids are thin and flat. The youngest proglottids, 

 4.0 mm. posterior to the head, are much broader than long, measuring 

 0.054-0.09 mm. long by 0.43-0.5 mm. broad. 



Nearly mature proglottids, about 32-36 mm. posterior to the head are con- 

 siderably broader than long. They measure 0.4-0.77 mm. long by 1.44- 

 1.36 mm. broad. In these proglottids spermatozoa are just beginning to 

 collect in the vas deferens and the outpocketings of the uterus are taking 

 form. Ripe or nearly ripe proglottids are usually longer than broad but 

 may be quadrate or broader than long. In the following measurements 

 (in'millimeters) length is stated first: 1.83 by 1.9, 1.16 by 1.79, 1.55 by 1.4, 

 1.94 by 1.36, 1.75 by 1.59, 2.32 by 1.55, 2.68 by 1.32. 



INTERNAL CHARACTERS 



Parenchyma. The parenchj^ma may l)e readily differentiated into cortical 

 and medullary portions which in structure and in relations to the various 

 organs are similar to the same portions in other species of Ophiotaenia. As 

 in other species of the group the parenchyma is characterized l)y large spaces 

 from which lipoid substances have been dissolved. These spaces are smaller 

 than in 0. fdaroides. 



Musculature. The musculature of the head and neck have not been 

 worked out owing to lack of sufficient material. In the proglottids muscles 

 are in general arranged as in 0. fdaroides. Muscles are weakly developed. 



