314 ^S', /. tSnuth — EarJy St<i<j(>.s of Illppa Udpoidn. 



stomaeli, however, shew, under the microscope, u small quantity of 

 vegetable matter, and it seems probable that the sand is swallowed 

 for the nutritive matter it may contain. 



Upon the beaches of Vineyard Sound the two sexes appeared to 

 occur in about equal numbers, although in museum collections the 

 males are often rare. This is probably due to the great inequality in 

 size between the male and female, the length of the carapax in the 

 larger females from Vineyard Sound being 20 to 22""", while in the 

 largest males it does not exceed 14"'"'. The sexes differ also in the 

 form of the telson (Plate XLVIII, figs. 7, 8) which is narrower and 

 more triangular in the male than in the female. 



Females carrying eggs were found during the entire month of 

 August, and during that period the embryos within the eggs were 

 nearly fully developed in many of them. Undoubtedly, however, the 

 term of carrying eggs extends over a much longer period than this. 

 The eggs are nearly spherical, "40 to -45"'"' in diameter, and the yolk 

 mass is orange yellow while the formed tissues of the embryo are 

 nearly colorless. Numerous attempts to obtain newly hatched young, 

 by keeping egg-carrying females in aquaria, failed from the parent 

 invariably casting off the eggs before they were fully matured. 

 Consequently I failed to secure the earliest stage of the zoea, for the 

 youngest individuals taken in the towing net were apparently in the 

 second stage. 



Very nearly fully developed embryos, when removed from the egg, 

 were found to possess all the normal articulated appendages of the 

 fully formed zoeae, but there was no appearance of lateral spines upon 

 the carapax and the rostrum was broad and obtuse. In this stage 

 the embryo agrees almost perfectly with the figure of the zoea of 

 Ilippa emerita from the coast of Brazil, given by Fritz Mliller in his 

 work entitled " Ftir Darwin."* The difference between the embryo 

 in this stage and the second zoea-stage (Plate XLV, fig. 1), in which 



* English translation, London, 1869, p. 54, fig. 25. The figure is accompanied by 

 the following paragraph : " The Zoea of the Tatuira [Hvppa\ also appears to differ but 

 little from those of the true Crabs, which it likewise resembles in its mode of locomo- 

 tion. The carapax possesses only a short, broad frontal process ; the posterior margin 

 of the tail is edged with numerous short setse." This, as far as I am aware, is the 

 only published account of the development of any sjDecies of Hippidse, except a note 

 by myself (in an article on " The Metamorphoses of the Lobster and other Crustacea," 

 in the Report of the LT. S. Commissioner of Fish and Fisheries, Part J, 187."5, p. 530) 

 recording the occurrence, at the surface in Vineyard Sound, of the young in what is 

 described further on in these pages as the megalops-stage. 



