212 Prof. J. 11. Henderson on a 



widely separated localities in the Indo-Pacific region. The 

 previonsly known species are two in number, viz. Hapalo- 

 carcinus marsvpialis, Stimpson, and Cryptochirus coralliodytes, 

 Heller; and Semper, who has studied both alive, has 

 given, in ' The Natural Conditions of Existence as they 

 affect Animal Life ' (1881), an account of the malformations 

 which they produce on living coral. 



Hapalocurcinus was originally described, somewhat im- 

 perfectly, by Stimpson (Proc. Boston Soc. Nat. Hist. vol. vi. 

 1856-59) from specimens ''found clinging to the branches 

 of living Madrepores, at the depth of one fathom in the 

 harbour of Hilo, Hawaii, March 1856." It is roughly 

 figured by Semper, who describes the "galls" which it 

 produces on branching corals belonging to the genera 

 Sideropora, Seriatopora, and Pocillopora. An upward 

 growth of coral is formed on either side of tlie crab, and in 

 time the latter becomes surrounded and enclosed so that it 

 cannot escape. Two fissures or slits at opposite ends of the 

 " gall " serve for the entrance and exit of water, and remain 

 open so long as the crab is alive. INIore recently Hupalo- 

 carcinus has been fully described and figured by Caiman 

 (Trans. Linn. Soc, ser. 2, Zocd. vol. viii. 1900), who gives a 

 valuable resume ot previous work on the coral-crabs. 



Cryptochirus was first described by Heller from the Red 

 Sea (" 13eitr. z. Crust. Fauna d. roth. Meeres," SB. Akad. 

 AVien,xliii. (1) 1861), where it was found inhabiting holes iu 

 coral. According to Semper it lives only in massive corals, 

 such as Goniastnea, Astnea, and Truchyphyllia, on which it 

 does not form "galls," but lives simply iu funnel-shaped 

 cavities or cylindrical pits due to arrested upward growth iu 

 the coral. With regard to the habits of the crab. Semper 

 makes the interesting statement that the cavities or pits 

 " are never closed during tlie lifetime of the crab, so that it 

 certainly would be able to quit its position. Nevertheless it 

 as cei tainly does not do so ; but the species T have observed 

 living thrust the fore part of their bodies very far out of their 

 peculiar cave-dwellings, so that only their pouches, i. e. the 

 hind part of the body, remained within." The species 

 described by A. Milne-Edwards under the name of Litho- 

 scaptus paradoxus (iu ]Maillard's 'Notes sur Tlsle de la 

 Reunion,' 2" ed. 186.'^, ii. Annexe V, p. 10) is apparently, as 

 has been pointed out by both raulst)n and Caiman, identical 



Pagurid which, so far as I know, iiiliabits coral is Troylopayunis manaar- 

 ensis of the present writer (Tnuis. Liuu. Sue, ser. 2, Zooi. vol. v. pt. 10, 

 1803) ; but 1 am unable to state if it causes abnormal growth. 



