356 STALK-EYED CRUSTACEA 



Section B. Pagurodea. 



Pagurodea . . Henderson. 



Paguriens . . H. Milne Edwards. 



Paguroidea . . De Haan. 



Pagiiridea . . Dana, Stimpson, Miers, Haswell. 



Carapace elongate, the posterior portion to the cervical 

 groove membranous, or less firm than the anterior portion. 

 First three pairs of legs well developed^ the last two pairs 

 small, and one or both chelate. Thoracic sterna linear. 

 Abdomen spirally twisted or extended, ancl usually- 

 membranous ; abdominal appendages present in both 

 sexes, consisting of a pair always present on the sixth 

 (penultimate) segment, and of usually a single biramous 

 limb present only on the left side of the second to the 

 fifth segments inclusive, the first three of these well 

 developed and ovigerous in the female. 



They are usually called Hermit crabs, and are found in 

 all seas in shallow and very deep water ; in hot countries 

 some of them live on dry land ; they protect their soft 

 abdomen usually by taking possession of an empty shell. 



Professor Henderson divides this section into two 

 branches according as to whether their gills are in the 

 form of flat plates {Laminibranchiata) or in the form of 

 round threads {Fibribranc/iiata), 



Family I. CcEnobitidae. 

 Family II. Paguridae. 

 Family III. Parapaguridae. 



Synopsis of the Branches and Families. 



I. Gills in the form of flat plates. — (Branch I., Lamiui- 

 branchiata.) 



