100 THE DEVELOPMENT OF 



Several authors have investigated the development of 

 Crangon, and an enumeration of their names may not be 

 out of place here in order that the present paper may 

 have an historical completeness. 



Rathke ('36 and '37) was the first to study the devel- 

 opment of the species, 2 but his account to-day possesses 

 but little more than historic interest, though he describes 

 the changes which occur within the egg. He compares it 

 with Palaemon and Astacus, but failed to see the gastrula 

 which is such a conspicuous feature in the latter genus, 

 according to the accounts of all observers. Captain Du 

 Cane describes and figures ('39, pi. vii, figs. 7 and 8) the 

 newly hatched Crangon, while K. Q. Couch ('44) de- 

 scribes the same species as it escapes from the egg. 

 Neither of these two papers has any present value. L. 

 Agassiz makes a curious statement regarding this and 

 some other genera. He says ('52) that Cuma is a larval 

 form, the so-called different species being the young of 

 Palsemon, Crangon and Hippolyte. This he claims to 

 have proved beyond a doubt because he has raised them 

 from the egg. A little later, C. Spence Bate showed that 

 the Cumacea were adult, whereupon Agassiz reiterates 

 ('56) his statement. Clans ( J 6l) describes and figures a 

 larva from Heligoland which he regards as the young of the 

 present species. It is farther along in its development 

 than any of the stages included in the present article. 

 E. Van Beneden ('70, p. 142, pi. x, fig. 20) has some 

 remarks upon the segmentation of the egg in this species 

 which are quoted and criticised on a subsequent page of 

 the present article. Smith ('73, p. 529) merely mentions 



2 Rathke calls his form Crangon maculosus, but it is clearly but a color-varia^ 

 tion of the widely distributed Crangon vulgaris. 



