VOL. XXXIV.] PHILOSOPHICAL TRANSACTIONS. 183 



rows in the ground. — The masseter muscle is also remarkably strong and 

 tendinous. — In like manner the depressor digastricus of the lower jaw, is ex- 

 ceedingly strong. The thyro-arytaenoid muscle, which is very conspicuous 

 under the sphincter of the gula, is subservient, by strongly constringing the 

 arytsenoid cartilages, to the production of the peculiar noise which these animals 

 make. There is nothing with regard to the other muscles described by Dr. S. 

 that requires particular notice.] 



Explanation of the Figures. — In fig. 3, pi. 4, ab represents the gula ; cd the 

 duodenum ; e the stomach. 



In fig. 4, EH represents a portion of the ileon ; gh a portion of the colon ; 

 HFi the caecum. 



Fig. 5, aa represents the valve of the colon, almost the same as delineated in 

 human subjects, only that it is nearly rhomboidal ; be the aperture of the ileum 

 into the colon. 



Fig. 6, K represents a portion of the cascum, whose lowest part is open to- 

 wards the colon, that the valvulae conniventes ooo may be observed.* 



Observations on the Lumen Boreale, or Streaming, on Oct. 8, 1726. By the 

 Rev. IV. Derham, F. R. S. N° 398, p. 245. 



There are two sorts of streamings, which have been noticed ; one, by way of 

 explosion from the horizon ; the other, by opening and shutting, without 

 shootings up, and swift dartings. Of the latter sort chiefly was that of Oct. 8, 

 1726, in which, although the streams or spires, or lances, or cones, or what- 

 ever else they may be called, were as large and remarkable as in the year 1715-6; 

 yet they exhibited themselves principally by the vaporous matter opening and 

 shutting, as if a curtain had been drawn and withdrawn before them. It began 

 about 8 o'clock, and soon streamed all round in the south, east and west, as 

 much, or nearly as much as in the north. Which was a thing not observed be- 

 fore in these phasnomena. 



These streams, or cones, were mostly pointed, and of dift'erent length, so as 

 to make the appearance of flaming spires, or pyramids ; some again were trun- 

 cated, and reached but half way : some had their points reaching up to the 

 zenith, or near it, where they formed a sort of canopy, or thin cloud, some- 

 times red, sometimes brownish, sometimes blazing as if on fire, and sometimes 

 emitting streams all round it. This canopy was manifestly formed by the matter 



• The subject of this dissection having been a dormant animal, it is matter of surprise that Dr. S. 

 did not examine the organs of respiration. 



VOL. VII. A A 4 



