164 . Mil. E, w. smAnx o>r the embryoNjo 



presumably been in the uterus for just over a year, since it is 

 incredible that they are of the same age as the minute specimens 

 noted above. Allowing for the incompleteness of the i*ecord, 

 subsequent n.ieasurements bear out this supposition remarkably 

 well. In February the embryos may measure from 35 to 42 cm., 

 while at the end of March we find one measuring 54 cm. 

 The last named is, according to our supposition, well on in 

 the second year of intra-uterine development. The figures 

 obtained for the months of December to March are sufficiently 

 consecutive to rule out the supposition that they represent the 

 lapse of a second year ; in which case we may suppose that the 

 rate of growth during this period is more rapid th.an during 

 the first year, namely, about 8 cm. per month. This estimate of 

 the I'ate of growth of the embryos during their second year, how- 

 ever, must be treated with caution ; for an embryo ( L) said to 

 have been captured in June only measured 47"5 cm., which would 

 reduce our hypothetical rate of growth to about 4 cm. per month. 

 The rate of growth during this period is probably liable to 

 variation; indeed, Ave find difi'erences in length of 12 to 15cm. 

 between embryos in the same uterus (H, K). On the whole it 

 seems reasonable to infer that the average rate of growth during 

 the second year of intra-uterine development is 5 to 6 cm. per 

 month. 



Dates of the capture of the larger embryos (M) are unfor- 

 tunately lacking ; but if growth continues at the rate indicated, 

 we may suppose that they were captured about July and were then 

 abDut 21 months old. This supposition, when taken with the 

 observed fact that a free-living young specimen (O) was cap- 

 tured in November, seems to indicate that birth may take place 

 in September or October, i.e., appi-oximately two years from 

 conception. In what state the young are born is a matter 

 of conjecture. The Table shows conclusively that the young 

 at birth are not much longer than the largest intra-uterine 

 specimens; moreover, they are approaching maturity, if not 

 already mature. If the young are born with the yolk-stomach 

 still distended it seems unlikely that in their unwieldy con- 

 dition they could have evaded capture hitherto. Hence the 

 suggestion oftei-ed above, namely, that the yolk store is used in 

 building up the reproductive system. It is extraordinarily diffi- 

 cult to believe that the huge paunch is lost in the course of a few 

 months without any apparent effect upon the growth of the 

 young fish. 



III. Uxtei'nal Features. 



The external features of the advanced embryo are amply 

 illustrated in two earlier papers (Lohberger, 4, and Shann, 6). 

 In order to save trouble in reference to other works, and at the 

 same time to render the descriptions in this paper more readily 



