MOTELLA AKGEXTEA. 39 



origin. Before tlie publication of Mr. Rice's paper. I supposed the young 

 fishes figured on Plate XII. to be the young of some Clupeoid, but the 

 figures given by him seem to leave no doubt that the young I figure on 

 Plate XII. belong to the Smelt." 



Motella argentea, Riiein. 



Plate XVIII. Fijjs. 1-6. 



The eggs of this species were found, during the summer of 1884, from 

 .May 25 to duly 25, but only on comparatively few occasions, and rarely 

 more than one or two at a time. It is by no means certain that this species 

 has been correctly identified, as no intermediate stages connecting Fig. 6 

 with the earliest stage described by Mr. Agassiz * have been obtained, and 

 as some uncertainty still remains with regard to the genus to which the 

 specimens formerly referred to Motella belong. In connecting this species 

 with that described by .Mr. Agassiz as M. argentea, we have to rely mainly 

 on the character and distribution of pigment in the newly hatched fish 

 (Fig. 6), and in a less degree on the size of the egg, presence of an oil- 

 globule, and the long and rather slender form of the embryo. 



The egg of this species is small, though a little larger than that of the 

 allied species described in Plate XII. The average size is about .78 mm., 

 the smallest measurement recorded being .75 mm. ami the largest .84 mm. 

 The globule is comparatively large, and colorless, and measures in most cases 

 .15 mm., reaching ,105 mm. in a single case. Two globules were found in 

 one egg, which soon coalesced, forming one of the usual size. July 13, 

 a similar egg was obtained, containing two cupreous-colored globules. The 

 egg measured .77 mm., and the globules, after coalescence, .16 mm. This 

 egg probably belonged to a different species, but the development was not 

 followed, so that we are unable to give further data for its identification. 



The egg of M. mustella, according to Brook, t varies from .655 to .731 mm. 

 (longer axis), and the oil-globule is only about .11 mm. In one lot of eggs 

 laid in an aquarium, the majority were found to have more than one globule, 

 and in every case of this kind the several globules coalesced before the em- 

 bryo hatched. As the eggs of this lot showed an unusual number of irreg- 



tssiz, Alexander. "On tin' young Stages of Os i I :s," Proc. Lmer k.cad A.rts and Sci., 

 .WIL, p. 294 (Plate \ "II. fig. 1). 



f Brook, George "On some Points in the Development ol < wstella, Linn.," Linnean Society's 



Journal, XVIII., 1885, pp 298-307. 



