1880. | Progress of American Carcinology in 1879. 501 
next discusses the growth of Polyonyx macrocheles. The last 
stages of the zoea obtained at Newport showed the enormously 
elongate spines of the carapax characteristic of the young of the 
porcelain crabs. All of the cephalothoracic appendages were 
present, the first two pairs of maxillipeds being large, biramose 
(schizopodal) and adapted for swimming. The third maxillipeds 
were rudimentary, and the ambulatory feet curled under the cara- 
pax. Six gills were noticed. The abdomen had six joints, and in the 
telson of those about to moult could be seen outlined the lacking 
segment with its appendages. From this stage the crab emerged 
at a moult without the intervention of a megalops stage. The 
young crab is nearly orbicular, and has not that “breadth of 
beam” characteristic of the adult, but resembles rather the genus 
Pisosoma of Stimpson. A bibliography of the embryology of the 
Porcellanide is given, but we notice that the figures of Guerin 
(in Ramon de la Sagra’s Historia fisica, etc., de l'Ile de Cuba, Paris, 
1857) are not mentioned. The last species in the present paper 
is Pinnixa chetopterana, which in the last zoeal stage has four 
long spines, one rostral, one dorsal and one from each postero- 
lateral angle of the carapax, arranged much as in the oft-copied 
figures of the zoea of Carcinus mænas. The cephalothoracic 
appendages have acquired a more or less complete development, 
the last six, however, being concealed much as in Polyonyx. 
From this stage the crab develops directly, the young, however, 
not having the enlarged fourth pair of feet which characterize the 
genus, though the family characters are recognizable. Ina supple- 
mentary note it is stated, on the authority of Prof. Smith, that a 
second species of Pinnixa found on the New England coast 
Passes through a megalops stage. 
The same author has worked out more completely the develop- 
ment of the common prawn of our coast and his paper forms 
a marked exception to the general poor quality of American 
biological work. In this species the cleavage of the yolk occurs 
in two planes almost synchronously, producing four cleavage 
spheres, from which the segmentation progresses regular ly until 
the morula stage is reached. No polar vesicles were observed. 
The gastrula condition was discovered within twenty-four hours, 
but concerning the origin of the hypoblast we are told nothing. 
1On the Development of Pa/emonetes vulgaris, Bulletin Mus. Com, Zoél., V, 
PP: 303-330, pls. 1-1v (Sept., 1879). 
