On the Geographical Distribution of Fishes. 251 



ill their relative size and position. The lahiinn, however, 

 thoii;i;h similar in form, is distinctly broader than the fore 

 extremity of the sternum (fi_<^. 2, h) ; while in L. dcsnltor it 

 is represented in figure 5 of Schiodte's plate as narrower. 



A single example of the adult female in the British Museum, 



Hob. Penang. 



Xatui'alists and collectors in Penang should endeavour to 

 find other examples of this genus, of which all our knowledge 

 at present is based upon the two specimens mentioned above. 

 Besides the interest attaching to the presence or absence of 

 spinners, they are the only spiders, as yet discovered, whose 

 abdomen is protected by articulated corneous transverse ])lates, 

 similar to those found in the orders Scorpionidea and Thely- 

 phonidea. 



XXXII. — On the Geographical Distribution of Fishes. 

 By Theodore Gill, M.D., Ph.D.* 



About 9000 species of living teleosteous fishes are now 

 known, variously distributed and found in greater or less 

 numbers in almost all the waters of the globe, fresh and salt ; 

 the greatest numbers of species, however, are found in the 

 tropical waters, and especially in the seas of the Indo-Moluccan 

 archipelago. The distribution of tlie types, especially of the 

 marine species, to a considerable degree coincides with ther- 

 mometrical conditions. In the polar and northern temperate 

 regions, for example, are found representatives of the families 

 of Gadoids or codfishes, Lycodoids, Stichaoids, Liparidoids, 

 Cottoids or sculpins, and others less known. In the tropical 

 regions many forms are distributed throughout the entire zone 

 (and therefore designated as tropicopolitan), this being espe- 

 cially the case with many genera of Labroids, Scaroids or 

 parrot-fishes, Pomacentroids,Gen-eoids,Serranoids or groupers, 

 Sparoids, Carangoids, and others — numerous species of these 

 families being found in torrid waters, while very few extend 

 far northward or southward. In the antarctic regions, again, 

 we have another combination of forms : typical codfishes and 

 the other tyjDcs characteristic of high northern latitudes are 

 wanting, but are severally replaced by peculiar groups, which 

 seem to fill an analogous place in the economy of nature, 

 having a superficial resemblance in general aspect, although 

 they arc not at all (comparatively speaking) related in structm'e. 



* Reprinted, with additions by the Author, from advance sheets of 

 ' Johnson's New Universal Cyclopfedia' 



