I. '21. 38 



Transitional forms are common between these two extremes. 

 E. variabilis was first described under that name by Milne- 

 Edwards and Bouvier in 1892, and there is no doubt that both 

 before and after that date many specimens were referred to 

 E. excavatus, which in reality belonged to E. variabilis. I have 

 investigated the records of '' E. excavatus,''' from northern 

 European waters, so far as I have been able, with the result 

 that I have found more than twenty specimens in the Irish 

 National Museum labelled " E. excavatus " or '' E. meticu- 

 losus.^' These were taken by various expeditions sent out to 

 the west and south-wxst of Ireland by the Royal Irish Academy 

 and the Royal Dublin Society in the years 1885-90, and were 

 recorded by Pocock (1889), Bourne (1890) and others. I find 

 that every one of these specimens, without exception, must be 

 referred to E. variabilis. Caiman (1896), writing after the 

 description of E. variabilis by Milne-Edwards and Bouvier 

 (1892) had been published, records only that species from the 

 same areas and does not mention any specimens of E. excavatus. 

 All the Irish records, then, really refer to E. variabilis. 



But even prior to 1892 the present species had been described, 

 though under a different name. Norman (1869) described a 

 species which he called Pagurus tricarinatus, from the Shetland 

 Islands. He afterwards came to regard this as really belonging 

 to the Mediterranean species E. meticulosus, and mentions his 

 specimens under that name in the " Museum Normanianum " 

 (1905). The three original specimens from the Shetland 

 Islands are in the British Museum. At my request Dr. Caiman 

 has kindly examined them with regard to the characters for the 

 separation of E. variabilis and E. excavatus, with the result 

 that all the three specimens wxre found to belong to E. variabilis. 

 Hansen, in 1908, suggested that this would prove to be the case. 

 Norman's name, E. tricarinatus, has of course priority over 

 E. variabilis, and Hansen (1908) uses it for the designation of 

 the species. But E. tricarinatus is preoccupied, having been 

 given to a Japanese species by Stimpson (1858), as is pointed 

 out by Henderson (1886). Hansen is also of opinon that the 

 specimen described by Sars (1885) under the name of E. tri- 

 carinatus (identified in the " Supplementary Notes " at the 

 end of Part II as E. meticulosus), really belongs to E. variabilis. 

 Specimens have also been referred to E. excavatus var. meticu- 

 losus from Scandinavian waters by Appellof (1906). I have 

 WTitten to Professor Sars with regard to the specimens recorded 

 by him in 1885, and in reply he tells me that after comparing 

 his original drawings with the description of Milne-Edwards 

 and Bouvier (1900), he is convinced that the Norwegian speci- 

 mens really belong to E. variabilis and not to E. excavatus {=E. 

 meticulosus). I have also received a letter from Dr. Grieg, of the 

 Bergen Museum, regarding the specimens recorded by Appellof 

 (1906). After examining them with regard to the differentiating 

 characters given above, he comes to the conclusion that 

 they all belong not to E. excavatus but to E. variabilis. 



