AKT. 7 CESTODE PARASITES OF BIEDS LINTON 39 



EECGRDS OF COLLECTIONS 



From Mergus serrator: 



(U.S.N.M., Helm. Coll. 7877.) 



1887, July 1.— One, length 16.15 mm. 



1913, January 1. — Twenty-five, small, maximum not much ex- 

 ceeding 12 mm. in length. 



1913, April 11. — The vial with label of this date contains cestodes 

 obtained from four birds, in the stomachs of which were 

 found Pholas^ cunners, and sticklebacks. There are very 

 numerous small strobiles from most of which the scoleces are 

 missing. Evidently the scoleces are rather firmly embedded in 

 the mucous membrane, and are broken off in attempts to remove 

 them. A piece of intestine, with worms attached, was in the 

 vial. It was difficult to detach them without breaking them. 



1913, April 17. — Numerous, small, scoleces missing. 



1913, April 28. — Many, as above. 



HYMENOLEPIS PACHYCEPHALA (Linstow) 

 Figures 127-130 



Scolex. — Subpyramidal, suckers rather large; rostellum longer 

 than scolex; hooks 10, slender, graceful, about 0.045 mm. in length. 



Dimensions of scolex mounted in balsam: Diameter 0.24; breadth 

 of sucker 0.09, length 0.10; length of rostellum 0.29. In one scolex, 

 the rostellum of which is fully extended but with hooks missing, the 

 rostellum tapers to a diameter of 0.03, then expands at the tip to a 

 diameter of 0.06. The retracted rostellum lies in the elongate, vesic- 

 ular sheath which extends as far, or a little farther, back than the 

 posterior border of the suckers. In one scolex (fig. 128) the circle of 

 hooks lay at the posterior end of the sheath with the hooks pointing 

 forward; in other cases the retracted hooks pointed posteriorly. 



Strobile. — Short; proglottides few and loosely attached. No 

 proglottides in which the genitalia had begun to develop, were seen. 

 The proglottides begin close to the scolex; they are rounded at the 

 margins. About eight proglottides were as many as were seen dis- 

 tinctly in any strobile, and the posterior three or four of these were 

 loosely attached. In those strobiles Avhich contained as many as eight 

 proglottides the last three or four were narrower than the first three 

 or four. 



Dimensions of formalin specimen : Length 8.68 mm. ; breadth of 

 scolex 0.17; length of rostellum 0.17, diameter 0.06; third segment, 

 length 0.056, breadth 0.22; fourth segment, length 0.063, breadth 0.21; 

 fifth segment, length 0.07, breadth 0.18; sixth segment, length 0.084, 



