OK THE EPITHEOA OF SEEIAL COEAiLA. 361 



time would be in great activity. But in such genera as Scarites 

 and Morio, and the innumerable allies of both, which copulate in 

 burrows or under bark, that is in confined recesses from which the 

 female cannot well escape, we see nothing but simple unmodified 

 tarsi. 



On these data it seems right to say that the males of Douhle- 

 daya have tarsi developed on the combined principle of Carabus 

 and Ghrysomela, and that this development is caused by the 

 combination of those influences which act separately in the 

 two last-named genera. 



DESCEIPTION OF PLATE XIV. 



On the Eeplacement of a true Theca or "Wall by Epitheca in 

 some Serial Coralla, and on the Importance of the Structure 

 in the Grrowth of Incrusting Corals. By Prof. P. Maetin 

 Duncan, F.E.S., Yice-Pres. Linn. Soc. 



[Eead JVovember 15, 1883.] 



DxTEiNQ- the discussions regarding the physiological value of some 

 of the structures of Madreporaria, great discrej)ancies have been 

 noticed in the opinions of naturalists. Amongst the structures 

 which have been carefully considered, no one has been more de- 

 bated than the epitheca. It has been pronounced to be worth- 

 less in generic diagnosis on account of its not being of primary 



