114. Mr. C. Spence Bate on the Development of Pagurus. 
observing that of P. platycheles (Pl. IX. fig. 4), I have taken 
advantage of the circumstance. It differs from the recognized 
typical zoéa of the common shore-crab (Carcinus menas) in the 
monstrous development of an anterior and two posterior cor- 
nuous processes to the carapace, and in the formation of the 
telson; but in its complete character it offers an intermediate 
condition between the brachyurous and macrurous Crustacea. 
It has the appendages of the cephalon and pereion developed to 
a similar extent with those of the Brachyura, whereas the telson 
and carapace bear a nearer resemblance to the same parts 
in the Macrura, from which they differ in degree only. In the 
carapace, instead of the rostrum and the posterior angles of the 
carapace being only just pronounced as in the macrurous z0éa, 
they are developed to a larger extent in the anomurous larve, 
and in the young of the Porcellane to nearly twice or three 
times the length of the animal; while the telson, instead of 
being shaped like the caudal fin of a fish, has in the Anomura 
the central portion sometimes produced to an angle posteriorly. 
Beyond this stage of the development of this species, or, I 
believe, any species of the Anomura, we have no sure know- 
ledge, except that which I stated relative to the genus G'lauco- 
thoé being a stage in the development of the genus Pagurus. 
The zoéa of Pagurus (Pl. LX. fig.1) is probably tolerably well 
known to earcinologists, but Lam not aware of its having been 
figured* or described. It has the anomurous character of a 
pointed rostrum and a projecting point at each of the posterior 
angles of the carapace, and the telson terminating in a gradu- 
ally widening fishtail-like appendage, fringed with a few ter- 
minal spimes—the appendages being developed rather on the 
type of those of the Brachyura than of the Macrura. During 
our expeditions we have taken specimens that we believe to be 
the zoéa of the same genus still further developed; we say be- 
lieve to be, because it is only from analysis that we have come 
to this conclusion, and have not the testimony of direct obser- 
vation that the one is the older stage of the other. 
That which we take to be the second stage of the genus 
Pagurus (Pl. IX. fig. 2) was captured toward the end of 
May, in a towing-net, in Plymouth Sound. From its general 
appearance my first impression was that it was the young of 
a Palemon; but closer: observation and a careful dissection 
of its parts induced me strongly to believe that it is the 
young of one of the anomurous group of Crustacea,—in the 
first place, the form of the carapace; in the next, the general 
divergence of its appendages from and their resemblance to 
those of the zoéa of a macrurous Decapod. ‘The superior 
* [Likewise figured by Fritz Muller, op. cit. p. 36, fig. 26,—EDb. | 
