HARDWICKE'S SCIEN CE-GUSSIP. 



253 



physiologists that the temperatiire of an animal's 

 body is in direct proportion to the activity of its 

 respiratory apparatus. Now, it is also familiarly 

 known that the temperature of birds ranges re- 

 markably high as compared with the mammalia. 

 But to those birds which dwell in the frigid zone 

 there would seem to be necessary 

 an exceedingly efficacious heat- 

 generating power, in order to sus- 

 tain life amid the rigour of that 

 terrible region. Such a state of 

 circumstances, therefore, we may 

 fairly assume to exist with respect 

 to the Great Northern Diver, and, 

 in short, generally throughout the 

 order Natatores, since these birds, 

 of all others, are most commonly 

 observed to inhabit the colder quarters of the 

 globe. 



On the whole, therefore, from the foregoing 

 observations it will readily be discovered that the 

 Great Northern Diver exhibits many and diverse 

 points of interest for the consideration of the com- 

 parative anatomist or physiologist. The bird is 

 extremely interesting, moreover, from another point 

 of view. Its cry is very peculiar and wild, recalling 

 as an appropriate association the bleak and barren 

 regions whence it comes. And as the twittering of 

 a swallow heard in the morning is denominated 

 beautiful by reason of its association with the cheer- 

 fulness of that sweet season, so does the cry and 

 aspect of the Great Northern Diver forcibly suggest 

 to us the wildness and desolation of the home 

 whence it springs— characteristics well calculated 

 to awaken peculiar emotions. P. Q. Keegan. 



MORE ABOUT CARBONIFEROUS EISH.* 



SOjVIE time since, when sojourning in the neigh- 

 bourhood of Leeds, my attention was drawn 

 to an outlier of the coal-measures on Baildon Hill, 

 an eminence a few miles distant from Bradford, the 

 height of which is about nine hundred feet above 

 the sea. On visiting this locality I discovered that 

 the pit, which had been sunk for coal, had been 

 abandoned, but the shale that had been brought to 

 the surface had not been removed. This shale on 

 being examined furnished me with remains of four 

 fossil fish, two species of PaUeoniscws, one species 

 of Ccelacanthus, and one olAcanthodes, which I will 

 briefly describe, as some of the readers of Science- 

 Gossip may be interested in the extinct forms of 

 life met with in the shales of the coal-measures. 



The genera just mentioned all belong to one of 

 Agassiz's great divisions of fish the Ganoids, which 

 have again been recently divided into the Lepidoga- 



uoids and the Placoganolds* The former of these 

 sub-orders is represented by the Lepldosteus, or 

 Gar-pike of North America, whilst the latter is 

 represented by the Sturgeon. Again, the fish con- 

 tained in the former sub-order had their bodies 

 covered with scales of a moderate size, and their 



Figf. i;2. Fossil Carboniferous Fish (Pa/iro«!scKs), restored. 



* Science- Gossip, 1872, p. 176. 



skeletons were more or less perfectly ossified, 

 whilst those comprised in the latter had their 



Fig. 1/3. Fossil Carboniferous Fish {Ccelacanthus), restored. 



skeletons imperfectly ossified, their heads and parts 

 of their bodies being protected by large ganoid 

 plates and scales. 



Fig. i;4. Spine of Fossil Fish (Acantkodes). 



Fig. 175. «, Scale oiFaloeoniscut, nat, size ; b, ditto magnified. 



The Lepidoganoids have been again divided into 

 several sub-orders, in one of which, the Lepidosteidce, 

 the fish of the genus Palceoniscus have been placed. 

 The members of this sub-order have rhomboidal 

 scales, which do not overlap one another ; and their 



* " Manual of Palaeontology," by H. A. Nicholson, p. 322. 



