( 12 ) 



PAGURIDES. 



Paguroida, Boas, Vid. Selsk. Skr., 6 Rjekke, Nat. og Math. Afd. 1. 2. 1880, p. 189. 

 Paguridea, Henderson, Challenger Anomura, 1888, p. 40: Ortmann, in Bronn's Thier 

 Reich, Maiacostraca, p, 1143. 



Paguridce, Milne Edwards and Bouvier, Crust. Decap. Hirondelle (Suppl.) et Princessee 

 Alice, Monaco, 1899, p. 51. 



Paguridea, Alcock, Cat. Indian Deep Sea Crust., 1901, p. 208. 



Carapace either elongate and subcylindrical, or broad and crab-like, the 

 front not fused with the epistome : rostrum present or absent. The abdo- 

 men is usually soft, asymmetrical, and spirally coiled ; or it may be merely 

 bent ; or flexed against the thoracic sternum as in crabs ; very rarely is it 

 symmetrical, straight, and dorsally well calcified. The tail-fan is usually 

 present and asymmetrical, occasionally it is quite symmetrical ; or it may 

 be absent. 



The eyes are never contained in orbits. The antennular peduncle is 

 flexed, and the flagella are generally short. The antennal peduncle is five- 

 jointed, the second joint almost always carries a moveable acicle. 



The flagella of the exopodites of the maxillipeds, when present, are flexed 

 inwards. The external maxillipeds are pediform. 



The thoracic legs never carry epipodites. The ist pair are chelate and 

 usually massive ; the 5th pair are always, and the 4th pair commonly, much 

 less developed than those in front of them. 



It is very unusual for all the abdominal somites to carry paired append- 

 ages : sometimes these may be present, in a modified form, on the ist or the 

 first two abdominal somites ; but as a genera! rule abdominal appendages are 

 present on one side only, usually the left side, of the 2nd-4th or 2nd-5th 

 somites: occasionally, in the male abdominal appendages are altogether 

 wanting. 



It is now generally agreed that the Pagurides spring from a common 

 stock with the Thalassinoid Macrura. Borradaile lays stress on this view by 

 including the Thalassinidea with the Anomura, which I think is going too far, 

 as being likely to confuse the systematist, while suggestive of little to the 

 morphologist, who already realizes that between the Macrura and the 

 Anomura — as also between the Macrura and the Brachyura — there are no gaps. 



Key to the Families of Pagurides. 



I. Uropods present: penultimate pair of thoracic legs much shorter than 

 those in front of them : — 



1. Abdomen straight and perfectly symmetrical, with all its terga well 

 developed and in contact, and with 5 pairs of symmetrical 

 appendages besides the uropods _ _ ^ PYLocHELiD.e. 



