Notices respecting New Booh. 53 



as in all these fishes, divided into polygonal discs, regularly piled 

 together, against which nerves ramify that terminate by succes- 

 sive bifurcations and anastomoses supplied from their elementary 

 fibres. How can we help seeing in this an electrical apparatus ? 

 It is true that its position is not the same as in the Torpedo, but 

 in the Gymnotus and the Silurus the organ is also situated in the 

 tail or around the body. These conclusions are further confirmed 

 by the following facts : I have proved that this apparatus is 

 wanting in the tail of the Torpedo and the genera Mustelus, 

 Scyllium, Squatina, Zygana, Acanthias and Carcharias. 



The presence of this apparatus in the tail of the Rays explains 

 the immoderate proportional length of this organ, its flattened 

 form beneath, and the absence of the inferior lobe on the caudal 

 fin, which scarcely exists in the Rays. The anal fin is also want- 

 ing in the Rays, it is also wanting in the Torpedos ; but all these 

 fishes have a complete caudal fin, whereas it is wanting in the 

 Rays, as I have just observed. 



I am indebted to the kindness of M. Bibrou for being enabled 

 to ascertain that the other fishes allied to the Rays {Cephalojjtei'a, 

 Myliobates and Pastinacus) whose tail is terminated by a thin 

 and extended whip or prolongation, do not possess this apparatus. 

 The whip is formed of a portion of the tail, which the electrical 

 apparatus would occupy if it existed. 



As we have just seen, this organ cannot be regarded as a 

 gland, for it has not the structure of one ; it does not possess an 

 excretory duct, it does not communicate in any part with the in- 

 side, and no gland receives so many nerves of animal life*. 



XIII. Notices respecting New Books. 



The Physical Atlas ; a series of Maps illustrating the Geographical 

 Distribution of Natural Phcenomena. By H. Berghaus, LL.D., 

 F.R.G.S. SiC and A. K. Johnston, F.R.G.S. S(C. 



A LTHOUGH the idea embodied in the publication before us is 

 -^ not here met with for the first time, yet it will jjrobably have 

 all the attraction of novelty for the general public, since we believe 

 that the work on which it is founded is not very extensively known 

 in this country. To those who know the Physlsche Atlas of Dr. 

 Berghaus, it will be a great gratification to find that the design has 

 been appreciated by the able editor of the National Atlas, and that 

 he has succeeded in obtaining the assistance, not only of Dr. Berg- 

 haus, but of some of the most distinguished followers of the sciences, 



• Nevertheless tlie proof of its being an electrical organ must depend 

 upon its power of giving electric shocks. Such a property, in our common 

 Rays, if it existed, could hardly iiave escaped the notice of fishermen, in the 

 constant liabit of handling large Kays, Skates and 'J'hornbacks iiinuudiately 

 after tlieir capture. — Kd. 



