280 KEPORT— 1867. 



cheles, we have taken advantage of the circumstance (PI. T. fig. 4). It differs 

 from the recognized typical zoe of the common shore-crab (Carciniis mcenas') 

 in the monstrous development of an anterior and two posterior coniuoiis pro- 

 cesses to the carapace, and in the formation of the telson ; but in its complete 

 character it offers an intermediate condition between the larvae of the bra- 

 chyurous 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 zoe, they are developed to a larger ex- 

 tent in the anomurous larva?, and in the young of the PorceJlam^ 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, we believe, any 

 species of the Anomura, we have no siire knowledge, except that which we 

 stated in the last Report relative to the genus Glaucothoe being a stage in the 

 development of the genus Par/urns. 



The zoe of Pagnrus (PI. I. fig. 1) is probably tolerably well known to car- 

 cinologists, but we are not aware of its having been figured or described. It 

 has the anomurous character of having a pointed rostrum and a projecting 

 point at each of the posterior angles of the carapace, and the telson termi- 

 nating in a gradually widening fishtail-like appendage, fringed with a few 

 terminal spines — 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 zoe of the same genus still further 

 developed ; we say believe to be, because it is only from analysis that we have 

 come to this conclusion, and we have not the testimony of direct observation 

 that the one is the older stage of the other. 



That which we take to be the second stage of the genus Pagurus (PI. I. 

 fig. 2) we took, in the latter end of May, in a towing-net, in Plymouth Sound. 

 Prom its general appearance our first impression was that it was the young of 

 & Palcfmon ; but closer observation and a careful dissection of its parts induce 

 lis 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 from and the resemblance to the appendages of the zoe of 

 a macrurous decapod. The superior antenna is developed upon the brachy- 

 urous type, but the inferior has the squamiform appendage of the macrurous 

 Crustacea. All the other appendages that pertain to the cephalon and pereion, 

 except the last pair of pereiopoda (and these are not developed, at least they 

 were not perceptible to oiir examination), have the macrurous type — a cir- 

 cumstance tliat would accord with the animal being that of an luideveloped 

 anomurous crustacean. The plcon and its appendages bear a very close resem- 

 blance to those of the larva of a prawn, since it is cquilaterally developed and 

 furnished with a pair of appendages, posteriorly and vcntraUy, attached to each 

 somite, the last of which is much larger than the others, and is evidently a 

 progressive stage in the development of the great caudal plates of the macni- 

 rous Crustacea. 



We attribute it to the geniis Pagmnis rather than to any of our other 

 anomurous Crustacea, because it differs from the known zoe of Porcellana, 

 and of that of Galatlxca wo have no knowledge ; but from the nearer 

 approach of these last genera to each other in their adult stage than to 



