SCUDDER ON FOSSIL INSECTS. 757 



breadtli of same 6,25"""; length of bodies not contracted 17.5"" ; breadth 

 of same 5.75"""; length of skins 25"'"; breadth of same 7.25™"'; length of 

 blades of mandibles 3.25""'; diameter of tracheae 0.6"'"'; of anterior spir- 

 acles 0.4'"'; distance of latter apart 2.75 """ . Chagrin Valley. 



Mitsca hibosa. — Another species is represented by a single body, and 

 one skin and its reverse, which seems to belong to the same. It is 

 closely allied to M. ascarides, but differs from it in some essential fea- 

 tures. When contracted, the body does not taper regularly from the 

 middle of the front half to the tail, but the whole hinder half is much 

 slenderer than the front, and toward the tip has nearly parallel sides, 

 so that the body is flask-shaped, and about twice as long as broad. A 

 similar, though not so abrupt, change of contour is seen in the skin. 

 The structure of the mandibles and of the trachea? may be seen to be 

 the same as in the preceding species, but the integument is naked, 

 being entirely destitute of any of the hairs which roughen the skin of 

 71/. ascarides. Length of contracted body 14"'"' ; breadth of same in front 

 7.5'""'; behind 3.75"'™ ; length of skin (a small one) 16"'"'; greatest breadth 

 of same 5.25"""; length of mandible blade 2.75"'"'; diameter of tracheae 

 0.75"'"'. Chagrin Valley. 



A third species is represented by three or four contracted skins, which 

 are too uncharacteristic to name, ihough it may be seen that they are 

 distinct from the others. As preserved, they are almost black ; the 

 skin is much wrinkled and smooth; the body pretty regularly and 

 bluntly obovate, nearly twice as long as broad; at the end of one, two 

 colorless oval patches lie united, side by side, pressed against the ex- 

 tremity, and doubtless represent the head, and prove it to be different 

 from the other species; it is, however, impossible to saj- what its affini- 

 ties may be. Length of body S.S™"'; breadth 4™"". Chagrin Valley. 



2lusca liydropica. — A fourth species is represented by two bodies and 

 a skin, which present an entirely different appearance from the preced- 

 ing three species, but which may temporarily be given the same broad 

 generic name. In this species, the form, even when contracted, is far 

 more elongated than in the others; the body is nearly five times as long 

 as broad, is broadest just behind the roundly pointed head, tapers rap- 

 idly toward it, but gently posteriorly to the middle, behind which it is 

 equal. In the skin, the part of the body preserved is equal and very 

 broad, excepting toward the head, where it rapidly narrows, the head 

 being well rounded or slightly produced ; the mouth parts, instead of 

 being withdrawn a little from the front extremity of the body, as in the 

 species already described, he at its very boundary, and the blades are 

 par'iiriel, instead of posteriorly divergent. The integument is covered 

 rather profusely with very short, conical, tapering hairs, scarcely more 

 than twice as long as their breadth at base. The larva is very distinctly 

 banded with darker and lighter colors, as the emptj' skin shows, the 

 posterior third of each segment being occupied by a very dark band, 

 darkest on the dorsal surface, while a faint pale transverse line breaks 



2 BULL 



