20 RESEARCHES IN HELMINTHOI.OGY AND PARASITOLOGY. 



Remarks. — This genus is divisible, by several well-marked char- 

 acters, into two distinct sub-genera. 



ist sub-genus. Streptostoma/^ — Body cylindrical, very strong^ly 

 marked with broad annuli. Mouth moderately large, round, bordered 

 by a collar (formed by the second annulus projecting beyond the 

 o-eneral outline of the body). (Esophagus divided into two distinct 

 pyriform muscular bulbs, with a small intermediate rounded bulb. 

 Tail four-fifths the length of the body. 



Strcptostoma agile. — Female. Body larvaform, cylindrical, nar- 

 rowed anteriorly and posteriorly, opalescent white, divided into from 

 sixty-one to eighty-eight broad annulations, of which there are 

 twenty-one from the mouth to the commencement of the ventriculus. 

 Tail very straight, occasionally slightly sigmoid, or bent at the point, 

 narrow and sharply pointed, inflexible and brittle. Mouth moder- 

 ately large, round, projecting ; pharynx almost null ; oesophagus 

 consisting of three bulbs ; the first elongated pyriform, strongly mus- 

 cular, measuring i-igyth inch long by i-3i9th inch broad ; second 

 bulb small, rounded, muscular, i-882d inch long by i-882d inch 

 broad ; third or true oesophageal bulb, pyriform i -294th inch long 

 by I -3 1 2th inch broad. Ventriculus dilated at commencement to 

 nearly the diameter of the body, afterwards straight and cylindrical 

 to near its termination, where it is slightly dilated. Rectum elon- 

 gated, pyriform. Generative aperture situated about twenty-four 

 rings above the anal aperture, which latter is placed between the 

 last two annuli of the body. Ovary double ; ova i-333d inch long 

 by I -400th inch broad. 



lycngth of body from 1-13 to i-iith inch ; breadth at commence- 

 ment of ventriculus i i i8th inch ; at middle of body 1-97 inch. Tail 

 from 1-16 to i-i5th inch long by i-888th inch broad at its middle. 



2d sub-genus. — Tlielastoina.-\ 



Body cylindrical, attenuated anteriorly, strongly marked with 

 moderately broad annuli. Mouth small, opening at the extremity 

 of a small papilla. CEsophagus divided into two distinct portions, 

 the first long and cylindrical, the second constituting the true 

 oesophageal bulb. Tail more than half the length of the body. 



Thela&toma attcnuatutu. — Female. Body attenuated anteriorly to 

 commencement of the ventriculus, opalescent white, divided into 

 from 140 to t6o annulations, of which there are from fifty-two to 

 fifty-seven from the mouth to the commencement of the ventriculus. 



* Streptostoma : — 2'7//£-ros" ^t azoiia. 

 t Thelastonia : — Qf^/.y^ et (rzoim. 



