XXIV.—Egg Attachment inCrangon vulgarisand other Caridea

Abstract

In the Caridea, unlike the allied Euphausiacea and Penæidea, developing eggs are attached by means of a “cement” to specialized non-pinnate ovigerous setæ on pleopods 1–4; in Crangon also to periopods 4 and 5. The presence of these eggs does not prevent flexure of the abdomen and execution of backward escape movements. The form of the abdomen differs in relation to habit, and this, together with the disposition of the ovigerous setæ, which varies greatly in different genera and in different pleopods of the same species, conditions the arrangement of the egg-mass. Ovigerous setæ increase both in numbers and in length with age; so do the number of eggs which have to be attached. There is concentration in the pleopods of “cement” glands identical with the tegumental glands which secrete the epicuticle which the “cement” resembles in all respects. Ducts run into the ovigerous setæ but it remains obscure where the “cement” emerges; possibly it dissolves its way through the integument of the setæ to emerge at many places simultaneously. Attachment of eggs in the Caridea may be associated with the many different habits exhibited; the developing eggs are protected and hatch out in the often restricted environment of the parent.