480 
it to be a sucker in a state of atrophy about midway between the func- 
tional and the very vestigial suckers of different species of the family. 
A stage of atrophy similar to this is found in the heads of plerocercoids 
of O. filaroides La Rue. In this species the fifth sucker continues to 
atrophy until it becomes nothing but a small group of cells surrounded 
by a basement membrane and imbedded in the tissues of the head and 
lacking a communication with the exterior. A vestigial sucker has 
been found in Acanthotaenia by Johnston (1909) who called it a mus- 
cle plug. 
Ophiotaenia nov. gen.: — Head globose or conical, flattened, smooth 
or furrowed, 
Fifth sucker vestigial. Suckers round or oval, with entire margins. 
Sexual organs as in family. Testes in two fields near vitellaria. Va- 
gina anterior or posterior to cirrus-pouch. In Crotalidae, Colubridae 
and Amphibia. 
The type of the genus is O. perspicua nov. spec. 
Ophiotaenia perspicua nov. spec.: — With characters of genus. 
Length up to 36 em. Max. breadth about 2 mm. Head conical, marked 
by four grooves, breadth 0,255—0,408 mm, thickness 0,306 mm, 
length 0,27 mm. Suckers four, circular or oval or nearly triangular, 
0,105—0,17 mm in max. dimension. Neck 5—7 mm long, slender. 
First proglottids short, mature ones quadrate, ripe ones longer than 
broad. Segmentation not evident. 
Genital pore marginal, irregularly alternate, at end of first third 
or half of proglottid. Vagina anterior or posterior to cirrus-pouch. 
Testes 150—215, situated in two fields. Cirrus-pouch reaching !/,—1/; 
across proglottid breadth. Cirrus slender. . 
Vagina dilated in first part, not crossing cirrus-pouch. Ovarian 
lobes long, flattened, irregular, made up of anastomosing tubes. Uterus 
with 20—30 lateral pouches on either side. 
Eggs with three membranes. Embryos 0,018—0,021 mm in dia- 
meter. In Nerodia rhombifer, Havana, Illinois. Material in collection 
of La Rue. 
Ophiotaenia grandis nov. spec.: — With characters of genus. 
Strobila very long (fragments measure 200mm). Breadth 2,75—4,25 mm. 
Neck 5—8 mm long. Head 1—1,2 mm broad at base of suckers. No 
fifth sucker. Suckers nearly circular, deep, muscular, 0,340—0,360 mm 
in diameter. . 
Genital pore irregularly alternating, near middle of proglottid 
margin. No genital papilla but sometimes a very deep depression im- 
mediately about genital pore. Testes large, 200—250 in number, in 
two broad lateral fields. Cirrus-pouch large, length equal to !/,—!/3 of 
