168 GARRISON., 



305 C. — ^Twenty-nine + centimeters long, head and neck missing, remainder 

 of worm in one piece from near the neck to gravid segments. 



305 D. — Twenty-nine + centimeters long, head and neck missing, remainder 

 of worm in one piece from near neck to gravid segments. 



305 E. — Four fragments, apparently parts of the same worm; two pieces, 1.5 

 centimeters and 9 centimeters long, .respectively, consisting of rectangular seg- 

 ments; two pieces, 2.5 centimeters and 13 centimeters long, respectively, consist- 

 ing of terminal, barrel-shaped segments. 



The complete specimen with head (305 A) was mounted in toto. Specimen 

 305 D and portions of 305 E were used for sections and digestion. In determin- 

 ing the various anatomical characters, all of the material has been studied. 



EXTERNAL ANATOMY. 



Head. — The head and neck unfortmiately became badly folded in mounting. 

 The actual breadth of the head as it lies is 256 /j.. Allowing for the folding, its 

 full breadth appears to be about 320 /j, but certainly can not exceed 400 fx. 

 Blanchard described the head as about 930 /jl broad by 510 /x. long. 



Leuckart does not give the general dimensions. 



The suckers in their greatest diameter measure from 105 to 125 ix, their lumena 

 from 30 to 45 ^. They are devoid of hooks. In Blanchard's specimen the suckers 

 measured 465 ij, in diameter with a lumen 100 /m in diameter. They also were 

 unarmed. Leuqkart does not mention the presence of hooks on the suckers of 

 his specimen. 



The rostelluvi is strongly retracted within the head and its contour can not 

 be made out. Imbedded in the head there remain about twelve hooks of. the 

 rostellum, of the peculiar "hammer-like" shape of Davainea. These hooks measure 

 23.5 to 25.2 fi long over all. The long root is rather sharply bent somewhat 

 beyond its middle and measures about 21 fi in length and is about 5.6 fi broad 

 as it joins the blade. The blade and the short root are continuous in one line, 

 each projecting about 2.8 fi, the blade being sharply curved and the short root 

 straight and blunt. 



In Blanchard's specimen the rostellum was invaginated, forming an apical 

 sucker 250 /x in its transverse diameter and 145 /jl deep with a deep cup-like 

 depression 83 //- in its greatest (transverse) diameter. The hooks were absent, 

 having evidently fallen off. In Leuckart's specimen the rostellum was plump, 

 retracted, about 100 /i broad and presented a circular depression at the apex of 

 the head. Around the equator of the rostellum was a ring of about 90 peculiarly 

 shaped hooks, each with a long, slightly curved root measuring 18 fji,, a short, 

 blunt, posterior root, and a blade about one-eighth the length of the long root, 

 with which it makes an angle of about 70°. 



Necli. — Because of the folding of the specimen the real breadth of the ne'ck 

 can not be made out with entire satisfaction, but it appears to be about the 

 same as the head, and it is not possible to make out any tendency to the broaden- 

 ing of the neck behind .the suckers as described by Blanchard. From behind 

 the suckers the neck gradually grows narrower and reaches a minimum breadth 

 of about 160 /i at a distance of about 2 millimeters from the tip of the head. 

 At about this same point the first sig-ns of segmentation are seen and the genital 

 primordia appear shortly after. 



Leuckart states that the breadth was "only 500 /j, just behind the head." 

 Blanchard's specimen measured 1,240 fj. a short distance behind the head and then 

 decreased to a minimum of 500 fx, at which point segiiients are already defined. 



Segments. — As stated, segmentation appears at about the minimum breadth 

 of the worm (160 /i) at a distance from the tip of the head of about 2 milli- 



