Family XI. Pceciliid^e. 117 



"Translated as follows : 



"A voyage to .California, to observe the Transit of Venus. By 

 Mons. Chappe d'Auteroche. With an historical description of the 

 author's route through Mexico, and the natural history of that prov- 

 ince. Also, a voyage to Newfoundland and Sallee, to make experi- 

 ments on Mr. Le Roy's timekeepers. By Monsieur de Cassini. 

 London: Printed for Edward and Charles Dilly, in The Poultry. 

 1778. (8°, 4p. 1., 315 pp., with 'plan of City of Mexico.") 



"Extract of a letter from Mexico addressed to the Royal Academy 

 of Sciences at Paris, by Don Joseph Anthony de Alzate y Ramyrez, 

 now a correspondent of the said academy, containing some curious 

 particulars relative to the natural history of the country adjacent 

 to the City of Mexico. Pp. 77-105. 



"It is undoubtedly this work that is meant in the statement that 

 has so largely gone the rounds of the periodical press, to the effect 

 that the Californian viviparous fishes were observed during the voyage 

 for the observation of the transit of Venus to Lower California, 1769. 

 A perusal of the accounts given, however, renders it evident that the 

 fishes in question were not Embiotocids. but rather Cyprinodontids, 

 probably of the genus Mollienesia. The account by Don Alzate 

 (pp. 89-91) is as follows: 



'"I send you some viviparous scaly fishes, of which I had formerly 

 given you an account. What I have observed in them this year is, 

 'If you press the belly with your fingers, you force out the fry before 

 their time, and upon inspecting them through the microscope, you 

 may discern the circulation of the blood, such as it is to be when the 

 fish is grown up.' If you throw these little fishes into water, they 

 will swim as well as if they had been long accustomed to live in that 

 element. The fins and tail of the males are larger and blacker than 

 those of the females, so that the sex is easily distinguished at first 

 sight. These fish have a singular manner of swimming; the male 

 and the female swim together on two parallel lines, the female always 

 uppermost and the male undermost they thus always keep at a con- 

 stant uniform distance from each other, and preserve a perfect 

 parallelism. The female never makes the least motion, either side- 

 ways or towards the bottom, but directly the male does the same.' 



"To this account is added a footnote (p. 90) containing the following 

 additional information : 



"'Don Alzate has sent those fishes preserved in spirits; their skin 

 is covered with very small scales; they vary in length from an inch 

 to eighteen lines, and they are seldom above five, six, or seven lines 

 in the broadest part. They have a fin on each side near the gills, 



