MODIOLA. 57 



i. Captain Brown described and figured a large number and variety of shells 

 under the name Modiola, quoting the references of previous writers. He included 

 several forms of Anthracomya in that genus. 



De Ryckholt included all the Mytiliform shells from the Carboniferous beds of 

 Belgium in the genus Mytilns ; of these M. CordoUaMus, M. fabalis, M. apici- 

 crassus, and M. palmatus are referred to Modiola by de Koninck. 



Baily referred a specimen from the Carboniferous shale of Foynes Island to 

 Myalina, but I have not been able to retain it in this genus, as the shell has 

 not a striated hinge-plate, and possesses an anterior lobe. I have considered this 

 term as a synonym of M' Coy's Modiola megaloha. 



De Koninck described and figured eighteen species of Modiola in his great 

 work {op. cit.^ pp. 174 — 180), four of which had been described previously by 

 de Ryckholt as Mi/tilus (mentioned above), and one by himself in a previous work 

 as Cardiomorpha. The new species are — 



Modiola princeps. 



— fusiformis. 



— lacryma. 



— impressa. 



— Meeki. 



— arguta. 



— .'' emaciata. 



Modiola gihherosa. 



— reniformis. 



— macrocephala. 



— cuneiformis. 



— spathuliformis. 



— f annulosa. 



On careful examination of the whole series of specimens now in the Natural 

 History Museum, Brussels, I am convinced that M. princeps and M. fusiformis are 

 the same shell as M. lingualis, now referred to Lithodomus, and I am doubtful 

 whether the Modiola Gordoliana may not also belong to the same species. The 

 type is somewhat crushed, and this may account for the flatter and more expanded 

 posterior end. The test is well preserved, and this may account for the accentua- 

 tion of the lines of growth. A second specimen has even a closer resemblance 

 to the British form. 



Of the remainder, the types of three, M. arguta, M. cuneiformis, and M. MeeJci, 

 do not appear to be in the collection. M. apicicrassa, de Ryckh., appears to me 

 to be in too fragmentary a condition to be recognised and to serve as a type, and 

 I doubt, with de Koninck, whether Modiola annulosa is correctly referred to that 

 genus. M. fabalis gave me the idea that it was the young of Posidoniella vetusta, 

 which it most resembles in the undulations which ornament its surface. 



Whether or not the shells which I still retain in Modiola are correctly 

 referred to that genus may be considered somewhat doubtful in the absence of any 

 knowledge of the internal anatomy of the shell. 



Portlock's Modiola Macadamii, var. lata, has a curious internal ridge, which 

 passes downwards from the umbo to the inferior border in the anterior part of 



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