172 Analysis of Scientific Books and Memoirs. 



low observe the time of their coming ;' and, as if their passage through the 

 air or the structure of their bodies made them sooner perceive the incipi* 

 ent changes of weather, the appearance and cries of birds have long been 

 considered to afford presages of the coming storm or the cessation of tlie 

 tempest. The institution of a College of Augurs at Rome may therefore 

 be conceived to have reference to something better than mere superstition; 

 and though the flight of particular species might, in the hands of interest- 

 ed individuals, be made to presage the wished-for result of a battle, or di- 

 rect a march already determined on, yet in the absence of the barometer 

 and thermometer the appearance or disappearance and cries of birds was the 

 signal to the husbandmen to sow his fields or to secure his crop. 



Jam veris praenuncia venit hirnndo.--~Ovid. 



Turn cornix plena pluvivvm vocat improba voce.— Firg. 



*' In this country the great migrations of birds take place in spring and au- 

 tumn. Those which arrive in spring come from warmer climates, and af- 

 ter incubation leave us in autumn ; and another host, chiefly Palmipedes, 

 from the arctic regions, arrive in autumn, and pass the winter on our lakes 

 and shores, departing again in the spring. Each species has a particular 

 mode of flight in these annual journeys, and a certain period of arrival and 

 departure. Assembled in large flocks the cranes cleave the air in the form 

 of a long triangle ; wild-geese fly in angular lines ; and the smaller birds 

 associate in less numerous families, and reach their destination by less con- 

 tinued flights.'* 



The third class of Vertebrated Animals or Reptiles is treated as the pre- 

 ceding classes. The orders are four, viz. Chelonian Reptiles or Tortoises ; 

 Saurian Reptiles or Lizards ; Ophidian Reptiles or Serpents ; and Batra- 

 chian Reptiles or Frogs. To this class belong the crocodile of the Nile, 

 known from the earliest times, and apparently much more common former- 

 ly than at present, as Scaurus during his sedileship displayed no fewer than 

 five of these animals in an artificial lake for the gratification of the Roman 

 populace ; the celebrated Chamaekon ; and the most dangerous serpents. 

 Fishes form the fourth class of Vertebrated Animals. These are divid- 

 ed into two sub-classes — distinguished as Cartilaginous or Osseous, and 

 into nine orders, according to the form and position of their branchia; or 

 gills, and fins. On this important class of animals the general details are 

 full, and the hst of species numerous. We quote only one passage. " The 

 amazing reproductive powers of fishes are well known. In the ovary of 

 the Cod in December were found 3,686,760 ova ; in the Flounder in March, 

 1,357,400 ; in the Herring in October, 36,960 ; and in the Tench 383,252. 

 And Bloch relates, as the result of an experiment regarding the reproduc- 

 tive power of the Carp, that, in a pond of seven acres, in which were plac- 

 ed four males and three females, the increase was 110,000 young carp,~a 

 number far too great for the size of the pond, and the necessary supply of 

 food. But this astonishing capability of increase is modified by a thousand 

 circumstances which regulate the number produced to the supply of their 

 food. Myriads of these ova form the food of different species ; and myriads 

 more of the young may be supposed to be destroyed in an element where 

 almost all are destined to become the prey of one another. But not with- 



