316 Miscellaneous. 



of the body. Pharynx very short and narrow ; oesophagus strongly 

 muscular, cylindrical, l-47th in. long by 1 -533rd in. broad ; oeso- 

 phageal bulb pyriform, 1-1 78th in. long, 1 -222nd in. broad. Ven- 

 triculus dilated alaeform at commencement, cylindrical throughout. 

 Rectum short, pyriform. Generative aperture forty-two annulations 

 above the anal. Ovary double ; ova l-333rd in. long by l-400th in. 

 broad. 



Length of body from 1-1 Oth to l-8th in. ; breadth at middle l-95th 

 in. Tail 1-1 4th in. long by 1-1 11th in. broad at middle. 



Hah. and Remarks. — Streptostoma agile and Thelastoma attenu- 

 atum are found together principally in the commencement of the 

 large intestine oiJulus marginatus, in numbers of from one to fifteen, 

 and less frequently in the small intestine with Ascaris ivfecta, in 

 numbers of from one to six. It is remarkable, that although I have 

 found from one to fifteen of these two genera in nine-tenths of the 

 animals examined, I have never yet been able to detect a single male. 



Thelastoma always has the mouth projected, whilst Streptostoma 

 has it retracted, producing, in some measure, but by no means wholly, 

 the difference in size of the oral aperture. 



At first I was inclined to think these two animals were different 

 stages of the same species, but the adults uniformly correspond to 

 the descriptions given, and in all cases contained more or less per- 

 fected ova. 



Their movements are active, wriggling the body in a sigmoid manner 

 and vibrating the delicate spiculated tail, which in sunlight resembles 

 a shining acicular crystal. 



Thelastoma, from its form of oesophagus and narrower annulations 

 and shorter tail than Streptostoma, occupies a position between the 

 latter and Oxyuris. 



Gregarina, Dufour. Body consisting of two distinct cells. In- 

 ferior cell the larger, marked with delicate, parallel, longitudinal 

 lines, (muscular ?) and filled with a fine granular matter, obscuring 

 one or two nucleolo-nucleated-organic cells. Superior cell placed in 

 a depression of the inferior, surmounted by a slight papilla in which 

 may be .detected two lines, apparently outlines, of an oral canal to 

 the interior of the cell which is filled with granular matter ; cell-wall 

 amorphous and transparent. 



Gregarina larvata. Body opake white, cylindrical or fusiform, 

 frequently considerably dilated at the middle of the upper third. 

 Superior cell a flattened or depressed sphere, received about one-half 

 into a depression of the inferior cell, surmounted by a papillary eleva- 

 tion with traces of a communication with the exterior ; interior filled 

 with a finely granular mass resembling oil-globules, and measuring 

 from 1-1 5,000th to 1 -7500th in. Length of cell, in smallest indi- 

 viduals, l-123rd in. ; in largest l-80th by 1-6 1st in. broad. Inferior 

 cell elongated, cylindrical or fusiform, not communicating with the 

 exterior nor with the interior of the superior cell ; filled with a mass 

 of granules resembling that of the superior cell, rendering the larger 

 individuals opake, but translucent in the smaller ones, and usually 

 obscuring one or two comparatively large nucleolo-nucleated-organic 

 cells, measuring from 1 -888th to 1 -308th in. in diameter. Cell-wall 



