12 Mindeskrift for J. Steenstrup. XXVII. 



that they must have been laid at different times, as not developed eggs, eggs with 

 embryos and empty shells are to be found among each other. 



The opening of the egg occurs in the manner that the shell splits in the front 

 part in a fissure which runs down the middle of the dorsal and ventral side to a 

 little beyond the middle (PI. I, fig. 7) ; two lateral valves are thus formed. I have 

 not been able to observe that the fissure is preformed in the egg-shell. 



It is mentioned above that the eggs are attached with, or generally more or less 

 imbedded in a glue-like substance. In the specimens, which are all preserved in 

 spirit, that mass is hard. The question then arises how the larvæ come out ; the 

 hard mass must prevent the opening of the egg, and even if the egg was opened, it 

 would be difficult or impossible for the larvæ to get out, and especially in the cases 

 where the eggs are lying in many layers above each other, and those at the bottom 

 thus are quite enveloped ; here the eggs lying farther down in the egg-mass certainly 

 must be destroyed. I suppose therefore, that the glue-like substance mentioned, 

 in its natural state, when the egg-mass is floating in the sea, is gelatinous, so 

 that it permits the egg to open itself and the larvæ to get out. There also exists 

 a communication which confirms this, Witlaczil says (1, c. 233) of the eggs taken on 

 the expedition of "Vettor Pisani" ", . . die von einer wahrscheinlich urspriinglich 

 gallertigen Masse umgeben waren. Diese Masse qnoll im Wasser wieder auf — •" It 

 is not said how the eggs had been treated before they were put into water, probably 

 they had been dried. One of my specimens also shows open egg-shells sitting quite 

 surrounded by the glue-like mass, which thus certainly must have been soft. 



When the larvæ have escaped they probably very soon undergo the first moult; 

 the specimen No. 18, which unfortunately has been destroyed, was a piece of drift 

 timber, on which eggs and cast larval skins were sitting. The first moult has then 

 occurred at the place where the larvæ had been bred, and certainly shortly after the 

 creeping out. Witlaczil states (l. c.) the same, founding his opinion on the faet found 

 in other Hemipteres. 



As to the mature embryos I can oiily confirm Witlaczil's communication, that 

 they do not quite fill the whole shell, and that the long middle and hind legs bend 

 down round the end of abdomen, and then along the dorsal side up towards 

 the head. 



According to what has been stated above the following may in general be said : 



The eggs of the Halobates are comparatively large, about ] mm long, elongated 

 oval or cylindric with rounded ends. The ventral side is arched, the dorsal side flat 

 or slightly arched ; the front end somewhat broader than the posterior end. The 

 colour varies gradually from yellowish white to red, as the development advances. 

 Ghorion is solid, thicker or thinner ; it is simple, without sculpture, or with a more 



