163 



ably llirthcr forward in development, some indeed being nearer to the elver stage than to 

 the broad Leptocephalus stage in which ail the June specimens are (Fig. 3—9 on Plate VIII). 

 The earliest developmental stages taken in June may be described first of all. 



(a) The appearance of the eel larvae {^Leptoccphakis brevirostris) in June. All 

 the June specimens are typical Leptocephalus brevirostris which only differ apparently 

 from the Mediterranean specimens described and figured by Grassi and Calandruccio in 

 being generally a little larger. The Italian authors unfortunately do not give a complete 

 list of measurements of their specimens, but they state (1. c. 1897, p. 9) that the length varied 

 from 60 to 77 mm. As can be seen from the accompanying table our Atlantic specimens 

 varied from 60 to 88 mm'. The measurement-curve shows a very distinct maximum 

 at 75 mm. the average size of all the specimens being 75-2 mm. For the rest the curve 

 resembles in every respect those usually obtained from a graphic representation of the lengths 

 of a large number of specimens belonging to the same year's group of one or other species. 



Length of the specimens of Leptocephalus brevirostris taken by the "Thor" in the Atlantic to the west 

 of the British Isles, June 1905 and preserved in formaline. 



° Number of specimens 



O Ü o o o 



00000000000 



0000000000000 



00 0000000000000 



0000000000000000 



00000000000000000000000 



OOOOOOOOOOOOOOOOOOOOOOOOO 



0000000000000000000000000000000000000 



00000000000000000000000000000 



000000000000000000000 



000000000000000000000 



0000000000000 



0000000000000 



000000 



00000 



88 



87 



86 



8s 



84 

 83 



82 

 81 

 80 



79 



78 



77 



76 



75 

 74 

 73 



72 



71 

 70 



69 



68 

 67 

 66 



65 

 64 



63 

 62 

 61 



60 

 59 



As can be seen from the figures on Plate VII the form undergoes some variation, some 

 specimens being narrower others broader. In none of them was there the slightest trace 

 of pigment except in the eyes in which the iris has a silvery sheen. In the living con- 

 dition all the specimens were quite clear like glass and transparent. 



I To see whether there was possibly any difference in the size according to the localities, the measure- 

 ments of the specimens taken respectively north and south of the Irish bank were separately distinguished. No 

 difference or practically none could however be detected. The lengths (in mm.) of the specimens taken north 

 of the Irish bank were as follows: 70, 71, 4X72, 3X74. 75, 2X76, 78, 2X79, 3 X 8°. 81, 82, 83. 



