VUl PREFACE. 



none from the North Pacific or from the Arctic regions of either 

 hemisphere, where we know that a Herring exists equally useful 

 and perhaps identical with the European species. Thus, for the 

 illustration of a single species, we may require a hundred speci- 

 mens; and not one of them will be superfluous. Again, we knoAV, 

 at present, that at least some 140 different species of Sharks exist, 

 a group of fishes which has always claipied a full share of attention 

 in a seafaring nation, the oil and fins of which form a valuable 

 article of trade, which, finally, from a scientific point of view, are 

 those of all living fishes in which the paheontologist takes the 

 greatest interest. Yet, with the imperfect state of all collections of 

 Sharks and Rays, our knowledge of them remains equally incom- 

 plete. Being compelled to limit, in most cases, our examinations to 

 the foetus or to examples not far removed from that stage, or to parts 

 of old individuals which can be determined in a general manner only, 

 we cannot follow the changes which their dentition imdergoes with 

 age ; and the palaeontologist, who chiefly depends on this character, is 

 unable to connect and interpret his fragmentary materials satisfac- 

 torily, unless supplied by the zoologist with the information which 

 is accessible to the latter only. This information cannot be obtained 

 without a collection requiring much space. Some Sharks exceed a 

 length of 30 feet ; and it is no exaggeration to ascribe an average 

 length of 5 feet to each of the 140 species known. 



" After having pointed out imperfections of the collection aa 

 they are apparent with regard to the present state of science, I have 

 to urge the necessity of keeping pace with the rapid progress of 

 ichthyology resulting from the efforts in other countries. Since the 

 period marked by the publication of the Ichthyology of the ' Beagle,' 

 ' Erebus and Terror,' ' Sulphur,' and ' Samarang,' the National Col- 

 lection has been left entirely to its own resources, and has been 

 dependent on the booty of private collectors. One of the chief 

 sources, the navy, which assisted Sir J. Richardson in bringing 

 together the magnificent collection at Haslar Hospital, now trans- 

 ferred to the British Museum, has failed entirely * since the great 



* "With the exception of the Magellan-Straits Expedition, to which Dr. Cun- 

 ningham was attached as naturalist. This gentleman made considerable col- 

 lections, part of which were deposited in the British Mu.seum. The number of 

 ppecimens of fishes obtained from this source is 78." 



