20 ILLINOIS BIOLOGICAL MONOGRAPHS [308 



Specific diagnosis : With the characters of the genus. Large worms from 1 00 

 to lOOOnmi. in length by 5 to 15mm. in breadth. Anterior end rounded, pro- 

 truding ; bothria faint. Strobila greatly elongate, depressed, maximum breadth 

 anterior to the middle, gradually tapering to the posterior end. Body crossed 

 by irregular ridges and furrows, and wavy at the margins in the adult, with 

 35 to 40 external segments anteriorly. Deep median groove on each surface 

 in the larva, two very shallow parallel grooves near the median line on the 

 dorsal surface in the adult. 



Cuticula 5 to 20/i in thickness, subcuticula 50 to llO^u. Nerve strands 50 to 

 100/x in diameter. Excretory vessels numerous in three layers, one close 

 beneath, among or just outside of the vitelline glands (cortical), another among 

 the main body muscles, and a third in the medulla. 



Genitalia from 0.05 to 0,20mm. apart. Genital cloaca a narrow transverse 

 sht, 0.18 to 0.20 by 0.02 to 0.03mm. into which open separately the cirrus, 

 uterus, and vagina, the latter constantly between the other two which alternate 

 irregularly from side to side. 



Testes interrupted only medially, 20 to 40 in transection, 115 to 145 by 

 80 to 85 by 45 to 55/x in dimensions. Vas deferens up to 35At in diameter, loosely 

 coiled above the cirrus-sac. Seminal vesicle small, close above the latter, 

 65 to 100 by 40 to 90/x. Cirrus-sac somewhat lateral, ovoid, with thin walls, 

 185 to 215 by 130 to 160 by 130 to 145/x. Cirrus proper within cirrus-sac, long 

 and coiled, 25/* in diameter. 



Vagina 15 to 30/1 in diameter, receptaculum seminis 75 to 90/i. Spermi- 

 duct short, 20 to 25 by 6 to 12/i. Ovary 0.5 to 1.5 mm. in diameter; wing great- 

 ly depressed, isthmus prominent and not in the median line but alternating 

 irregularly from side to side opposite the cirrus-sac; ova in same 12 to 15/x in 

 diameter. Oocapt 18 to 20/i in diameter, oviduct 15 to 20/i. Vitelline reservoir 

 ellipsoidal in shape, sharply separated from the duct on either side, 40 

 by 30/i. Vitelline follicles irregular in shape, 50 to 70 by 15 to 30/t, in a layer 

 close beneath the subcuticula and broken only ventrally. Shell-gland composed 

 of much elongated cells with enlarged bodies and narrow necks connecting with 

 the oviduct for 30/i of its length. Uterus a mass of coils in the median line, 

 0.4 to 0.6mm. in diameter, that of the tube being 30 to 60/c. 



Eggs, 50 to 65 by 30 to 42/t. 



Habitat: As larvae in the body-cavities of teleosts; adults in the intestines 

 of wading and diving birds. 



