268 AIR-BREATHERS OF THE COAL PERIOD. 



their base there is an ash-coloured arched bar bounded on the 

 outer side with black. The under side differs principally in being 

 paler and destitute of the angular and arched bars at the base of 

 the upper and lower wings.* These moths, when in health and 

 especially in sunshine, connect themselves and lay eggs in a few 

 days. If they do not develope their wings or the temperature is 

 low and without sunshine the males do not seek after the, females 

 hence the eggs laid are often, under these circumstances, unpro- 

 ductive. 



Art. XXI. — The Air-Breathers of the Coal Period in JYova 

 Scotia ; by J. W. Dawson, LL.D., F.E.S., &c. 



{Continued from page 175.) 



VIII. — Htlonomus Actedentatus. 



Plate VI, Figs. 1 to 16. 



This species is founded, on a single imperfect specimen obtained 

 by me at the Joggins in 1859, and described in the Journal of 

 the Geological Society, Vol. XVI. In this description, I men- 

 tioned, as probably belonging to this species, certain detached 

 bones which I have since found reason to attribute to Den- 

 drerpeton Oweni. These did not however materially interfere 

 with the characters of species, which I shall give here from 

 the fragments represented in Plate VI, Figs. 1 to 16, and which 

 occur together in the matrix in such a manner as to render it 

 certain that they belonged to the same individual. 



In size, H. aciedentatus was about twice as large as the species 

 last described. Its teeth are very different in form. Those on 

 the maxillary and lower jaw are stout and short, placed in a 

 close and even series on the inner side of a ridge or plate of bone. 

 Viewed from the side they are of a spatulate form, and pre- 

 sent a somewhat broad edge at top as in Fig. 4. Viewed in 

 the opposite direction, they are seen to be very thick in a direc- 

 tion transverse to that of the jaw, and are wedge-shaped as in 

 Fig. 5. There are about forty on each side of the mandible, and 

 about thirty on each maxillary, as seen in Figs. 1, 2, and 3, of 



* Sir H. Jardine's description of Sturnia Cynthia, and corresponding 

 in every particular to ailanthus silk moth. 



