24 REPORT — 1855. 



been supplied by our friend C. S. Harris, Esq., of Budley Salterton, and from 

 Falmouth we have recently been indebted to our excellent friend J. Web- 

 ster, Esq., for the results of extensive dredgings. 



From the coasts of Northumberland and Durham we have received many 

 species through the kindness of Joshua Alder, Esq. From Weymouth we have 

 been assisted by Prof. Williamson of INIanchester, and P. H. Gosse, Esq. 



To our excellent friend P. T. Smyth, Esq., who not only supplied us with 

 the result of his own industry, but frequently placed his yacht at our disposal 

 for dredging purposes, we cannot be too thankful, since it is greatly through 

 his means that we have been successful in obtaining a very large collection 

 of South British species. 



Mr. Boswarva, so weW. known in the neighbourhood of Plymouth for his 

 knowledge and skill in preserving the marine Algae, has frequently sent us 

 specimens. So also has our valued friend and companion Howard Stewart, 

 Esq., Student of Anatomy at the Royal College of Surgeons; also his 

 brother, Mr. Charles Stewart. 



George Parker, Esq., of Jersey, and recently Mr. Edwards, an industrious 

 naturalist at Banff, and Mr. John Loughor of Polperro, and other kind 

 friends have furnished us with what specimens accident or good fortune 

 may have brought within their reach *. 



For the purpose of identifying species with Leach's and Montagu's 

 types we visited the British Museum, where we received every assistance 

 and kindness from Dr. Gray and Mr. White, whose ' Catalogue of British 

 Crustacea ' has been a valuable handbook of species, and much used by us 

 in our progress with the subject. Nor can we forget Mr. Kippist, the Li- 

 brarian of the Linnean Society, who most obligingly procured for us many 

 books of the Society which it was necessary should be consulted. 



The Homologies. — In comparing the external organization of the Amphi- 

 poda with that of the 3Iacroura, the observer is attracted by the absence in 

 the former of the great cephalo-thoracic buckler or carapace. This in the 

 higher tribes is the result of the exaggerated development of some of the 

 anterior segments of the head. This loss of the carapace is also accom- 

 panied with a separation into distinct annules of the whole of the remaining 

 portion of the animal, whilst the cephalic region, including the seven anterior 

 segments, assumes no greater space or higher importance than any of the 

 other individual segments. 



If a careful examination of the cephalic ring be made, it will be found 

 that there evidently are the same relative parts, without that monstrous deve- 

 lopment which in the higher types produce the carapace. 



It has elsewhere been shown ■]-, upon evidence which appears to us impos- 

 sible to be misunderstood, that the anterior segments exhibited in the cara- 

 pace, viz. the antennal rings, gradually diminish in importance inversely 

 with the development of the mandibular ; that whereas the Ibrmer build up 

 the larger portion of the carapace in the JBrachyura, the mandibular seg- 

 ment in the lowest of the Macroura type {Diastylis, Ciima, ^cj) completes, 

 to the almost total exclusion of the anterior segments, the entire carapace. 

 This increasing development of the anterior or cephalic segments is in 

 accordance with the consolidation of the nervous system, and vice versa, the 

 separation of the nervous cord into distinct ganglia is coincident with a cor- 

 responding decrease in the importance of the carapace. 



* In the forthcoming work on the British Edriophthalma, we shall identify the species 

 with their habitats upon the authority of our kind friends. 

 t Annals of Natural History for July 1855. 

 X Vide paper on the British DiastylidcB, Ann. Nat. Hist, for June 1856. 



