DUBIOUS DOMICILES 169 



the friction of its body, but Aurivillius shows that there 

 is a, secretion from glands in the sides of the carapace 

 adapted for the purpose, and that the joints in the fourth 

 and fifth pairs of legs of lHupagurus are nicely arranged to 

 assist in distributing the secretion. 



Paguropsis, Henderson, 1888, is regarded as holding a 

 unique position among Hermit-crabs, inasmuch as the last 

 two pairs of legs of the trunk are subdorsally placed, and 

 the unpaired appendages of the pleon are on the right side 

 instead of the left. Dr. Henderson observes that ' among 

 the Pagurids generally, the soft abdomen, as a result of 

 its being thrust into a Gastropod shell, the spiral of which 

 is normally right-handed, has assumed a similar curve, and 

 the original right side thus closely applied to the columella 

 loses its appendages.' The two specimens taken at a depth 

 of about a hundred fathoms off Tables Island, were free, but 

 the character of the pleon makes it probable that it was 

 protected in some way. The position of the appendages 

 on the right side might be explained as adapted to some 

 species of Gastropod with a left-handed spiral, but the fact 

 that the pleon is simply bent on itself points to some other 

 kind of dwelling. 



Pylocheles, A. Milne-Edwards, 1880, has the carapace 

 completely calcified, the chelipeds equal, the pleon sym- 

 metrical and well developed with broad semi-calcareous 

 terga and paired appendages of one kind or another on the 

 first six segments, those of the sixth segment forming with 

 the telson a powerful swimming fin. This remarkable 

 genus is said to form a connecting link between the Pagu- 

 ridee and Thalassinidse. The type species, PylochpJes 

 Agassizii, A. Milne-Edwards, was dredged by the Ilake 

 from a depth of 200 fathoms off Barbados, and found in 

 the hollow of a piece of sandstone, the mou1 h of which was 

 closed by its claws, as the mouth of a shell is by those of 

 of an ordinary hermit. Pylocheles spinosus, Henderson, 

 which is depicted on Plate VII., is Australian. Nothing 

 is known aboat its mode of lodging itself. Eor this genus 

 Mr. Spence Bate in 1888 established the family Pyloche- 

 lidse, which he placed between the Galatheidee and Thalas- 



