408 Miscellaneous. 



throws out the sand that has fallen on the passage to his door, and 

 then comes out again at the end of some minutes to scoop out a 

 second furrow in another direction. When this manoeuvre has been 

 repeated eight or ten times the shell is completely buried under a 

 little hill of sand with rounded top, trenched with furrows disposed 

 starwise, and pierced by a hole giving access to its concavity. 



This hole is, in general, perfectly round, and just large enough 

 to allow the master of the house to pass. Such a hole could not 

 preserve its shape in sand if the grains forming its walls were 

 not agglutinated by the mucus secreted by the skin of the animal 

 when lying in its hole. 



AVhen his house is constructed — a house which, as we shall see, is 

 a true nest — the male endeavours to entice the female to his home. 

 For this purpose he comes out of his sanctuary, swims rajndly 

 towards her, draws near her by little jerky bounds, pushes her fre- 

 quently with his snout, and then returns rapidly towards his 

 nest as if to show her the way to it. If the female, as usually 

 happens, refuses to follow he returns to the charge, touches her again 

 with his snout, and again makes a pretence of returning to his den ; 

 often he repeats this manoeuvre five or six times together : then, 

 discouraged by the indifference of the female, he reenters his 

 dwelling, but not for long ; for, at the end of a minute or two, often 

 less, he comes out of it again and recommences his solicitations. 

 One evening I observed a male wlio, in the space of three hours, 

 came out of his hole seventy-eight times, and invited the female a 

 hundred and sixty-eight times to share his nest. 



When the male approaches the female to solicit her to follow him 

 his colours suddenly become brighter, he erects his dorsals, raises 

 his head vigorously, and spreads his opercles : at times also his body 

 is agitated by a very visible trembling. When he has returned to his 

 nest, his head, which he lets j)roject out of the hole, becomes quite 

 white, and he respires with a febrile activity which is in complete 

 contrast with the normal respiratory rhythm. If the female 

 approaches the agitation of the male becomes extreme ; he retires 

 quicklv into his hole several times in succession, as if to call her in ; 

 but often the female retreats without deigning to respond to these 

 advances ; then he resumes his station, and soou recommences the 

 solicitations described above. 



At length, if the female decides to enter the sht-U with him. he 

 remains at the entrance to the nest and waits for her to lay in a 

 state of extreme agitation ; but often she escapes immediately, in 

 spite of the manifest efforts which he makes to prevent her from 

 goinfi; out by extending his pectorals transversely. When the female 

 consents to remain the laying commences. To do this she proceeds 

 to the ceiling of the nest by the aid of the cupping-disk which she 

 bears on her ventral surface and dt-posits her eggs by the way, which 

 cling to the internal face of the shell by means of glutinous fila- 

 ments regularly disposed at one of their poles. These filaments, 

 secreted by the cells of the follicle, liardcn after remaining for some 

 hours in sea-water. 



After a certain number of e2:irs liave been laid the female resumes 



