1850.] 101 



Hammerschmidt, who named it Oxyurls Diesingii, but as it is considered a doubt- 

 ful compliment to name intestinal worms after persons, in placing it in the genus 

 Streptostoma, I have also changed the specific name. The individuals from which 

 my description is taken were the largest I found. 



Sub-genus Thelastoma. Proc. Acad. Nat. Sci. 1849 p. 231. 



2. Thelastoma appendiculatum. Body cylindrical, narrowed anteriorly 

 and posteriorly, white, translucent, shining, strongly annulated. First division 

 of the oesophagus moderately long, cylindrical ; second portion short, broad, and 

 pyriform, ventriculus dilated cordiform at commencement, becoming rapidly 

 narrowed and cylindrical, and sending off posteriorly a large and long pyriform 

 diverticulum or coecum, afterward cylindrical to termination, and forming a 

 single short convolution just posterior to the generative aperture. Tail straight, 

 spiculate, one-fourth the length of the body. Eighty five annulations to the body 

 of which there are twenty- eight from the mouth to the commencement of the ven- 

 triculus. Generative aperture twenty-six annulations from the anal aperture. 

 Last annulation furnished with two short spines projecting backward. 



Length of body 1 line to 1-lOth of an inch; breadth at ventricular commence- 

 ment 1-lOOth inch, at middle l-80th inch, at anus 1-lCOth inch; tail l-50th inch 

 long, breadth at middle l-SS8th inch ; first portion of oesophagus 1-SOth inch 

 long, l-533d inch broad; second portion l-240th inch long ; neck of do. l-6C6th inch 

 broad ; body of do. l-250th inch ; commencement of ventriculus l-200th inch broad ; 

 cylindrical portion l-400th inch ; diverticulum of ventriculus l-66th inch long 

 by l-266th inch broad. 



Ovum semi-oval, l-258th inch long, by l-666th inch broad. 



Habitation. Found in the intestinum tenue of the domestic cockroach (Blatta 

 orientalis,) with the former. 



3. Thelastoma labiatum. Body white, translucent, anteriorly stronely 

 annulated. Papilla of the mouth dilated, six lobed. First portion of oesophagus 

 cylindrical, second portion broad, pyriform ; ventriculus sub-cordiform at com- 

 mencement. One hundred and fifty annulations, of which there are forty from the 

 mouth to the commencement of the ventriculus. 



Length of body l-22d inch; greatest breadth l-200th inch: length of tail l-40th 

 inch; length of first portion of oesophagus l-120th inch; breadth 1-lOOOth inch ; 

 second portion l-320th inch long by l-400th broad ; breadth of ventricular dilata- 

 tion l-266th inch. 



Ovum oval, l-333d inch long, by l-IOOth inch broad. 



Habitation. Found in numbers of from one to a dozen in the intestine of 

 Polydesmus virginiensis, 



4. Thelastoma robustttm. Body white, cylindrical, narrowed anteriorly 

 and posteriorly. First portion of oesophagus long, cylindrical ; second portion 

 broad, pyriform. Commencement of ventriculus dilated, oval, afterwards cylin- 

 drical. Articulations of body 212, of which there are forty from the mouth to 

 the commencement of the ventriculus, 102 from the latter to the generative 

 aperture, and from this to the tail 70. 



Length of body 2 lines ; breadth at ventricular dilatation l-75th inch; at sixth 

 annulation from mouth, only l-320th inch; at middle l-66th inch; I'ust above 

 anus l-75th inch ; tail l-22d inch long by 1-lOOOth inch broad at middle ; first por- 

 tion of oesophagus l-50th inch long by l-500th inch broad ; second portion l-17Sth 

 inch long by l-200th inch broad ; ventricular dilatation l-105th inch broad. 



