FISSURELLlD.t 



FIS3URELLID.E. 



but it will be seen that the anterior edge of the shell is always some- 

 what emarginate, while in the situation of the bronchia*, the anterior 

 fissure in the mantle of the animal, and in the position of the vertex 

 in the shell, they exactly resemble each other ; we therefore consider 

 the Parmopkori of Blainville and Lamarck as elongated and com- 

 prated EmaryinuUr." Deshayes, in hi edition of Lamarck (1836), thus 

 i Tpronsos his opinion : " Cuvicr was the first who gave anatomical 

 details of the genus Kmaryinula, and he made it appear how much 

 analogy existed between it and Fumrrlla. There exists, nevertheless, 

 between these two genera sufficient differences to warrant their con- 

 tinuance in systematic arrangement. But it is not so with regnnl to 

 Parmopkortu. M. de Blainville, to whom we owe this lost genus, 

 and who was the first to make the animal known, had judiciously 

 preconceived the necessity of its junction with Emarginula. In 

 fact, not only have the ouinmla of the two genera a perfect 

 analogy, and not only can they be with difficulty distinguished 

 in some cases and in some species, but the shells themselves, 

 as might have been supposed h priori, offer some passages from 

 the one genus to the other, the number of which will be aug- 

 mented by new researches. When we have before us a fairly complete 

 series of living and fossil species belonging to the two genera the 

 following observations occur : The two fossil species of Parmophorut 

 have no trace of a marginal notch ; Parmophoria Australia has the 

 anterior border a little depressed in the middle, aud within the shell 

 is to be seen, corresponding with this depression, a small crest indi- 

 cating the separation of the mautle. Among the species of Emargin ulit 

 brought home by Messrs. Quay and Qoimard there is one which they 

 name Parmopholda, and which would seem to be entirely deprived 

 of a marginal notch. In the Subemarginula of M. de Blainville the 

 shells have no longer this notch, but they have within a deep ridge 

 (Hilton) in the place of it. In other species, as in Emarginula rubra 

 of Lamarck and E. elegant of M. Defrance, the small interior ridge is 

 terminated on the border by a very short notch ; and from this 

 commencement to the termination of the series of species we see 

 this notch become deeper and deeper, and change at lost into a deep 

 slit occupying one half of the height of the shell." After dwelling 

 upon the differences of the shells in other points of external form, 



M. Deshayes observes that the general aspect of the shells leads the 

 zoologist to separate the genera, while the structure of the animals 

 tends to fuse them into one, and thus concludes : " M. Sowerby has 

 come, as we have before said, to this conclusion, and in his ' Genera 

 of Shells' has united the Parmophori to the Emarginulcc. This 

 example will without doubt be followed by other zoologists." 



We entirely agree in this conclusion, and consider the following 

 arrangement of Emarginula; by De Blainville as merely arbitrary, 

 and calculated to assist the conchologist and fossil zoologist in his 



subdivision of this molluscous form. 



Animal of Emnrginula. 



Shell of Emerfinula (E. arnica). 



a. Species whose notch is in the middle of the back of the shell, and 

 far from reaching the edge. (Kimula ? or Kimulaire > of Defrance.) 

 Kx. Emarginula, BlainriUii. 



marginula Bltmrillii. 



P. Compressed species, whose anterior border is deeply notched, and 



the summit strongly marked. (Les Entoilles.) Kx. Emarginula 



flitura. 

 y. S|..-cies utill more compressed, whose anterior border is only bent 



into a gutter, and whose summit is still evident. (NubemaryintU<e.) 



Kx. Emnrginula emargtnata. 



Emarpinula Jiuura. 



a, natural slw ; t, mifpilficd ; f, tn(tniBed, the shell turned up, showing the 

 animal In titu. 



fmarginata. 



S. Species very much depressed ; the summit very little developed 

 and prtemedian, with a small notch. Ex. Emarginula depntta. 



Einarginula dtprtua. 



Parmophorut (Scutum of De Montfort). Kx. P. Autlralit, syn. 

 clonyatui (Patella ambigua, Linn.) 



Localities, seas of Australia and New Zealand. 



fannopliona Australis. 



Emarginula and Parmophoriu are littoral shells like Patella, and 

 their habits ore similar to those of the last-named genus. Emargi- 

 nula has been found at depths ranging from the surface to 11 

 fathoms. 



fouil FaiureHidte.Q. B. Sowerby says that a few fossil species 

 are found in the truly marine formations above the Chalk. Deshayes, 

 in his Tablex, enumerates 33 living species and 8 fossil (tertiary). 

 Of these, P. (Jrtrea, J > . coitaria, and P. ncglecta, he states to be both 

 living (the two former in the European and Indian oceans, and tin- 

 Utter in the Mi-diti-rninean) and fossil, in the pliocene (all three) and 

 mioceue (the two latter) periods of Lyell (Sicily, Italy in the sub- 

 Apeunine beds, English Crag, and Totirniue). He mentions three 

 Sicilian specios, three Italian (Hub-Apemiine beds), one in tin- I'.n^lirli 

 Crag, two at Dax, two in Touraine, two at Angers, and four at I 

 The Fiuurella Noachina of Deshayes, Patella Noac/timt ( Ly<-H, i* 

 living in the northern seas, and found fossil in Sweden and Norway. 

 It appears to be between a FitiurcUa and an Emarginula, and it is not 

 iin|Ht<iblc that it may be a Fiuuretta in a young state. 



O. B. Sowerby (' Genera of Recent and Fossil Shells') observes that 

 the fossil Emarginula are scarce. " They occur," odds that author, 

 " in the calcaire grosser and its contemporary strata ; in the crag of 

 Suffolk, Essex, and Norfolk ; and in the Bath oolite. They are very 

 elegant little fossils, particularly Lamarck's K. ctyptato. We cannot 

 consider his P. elongatut as a species of this genus, for its verti-x in 

 anterior, as its muscular impression demonstrates; consequently wo 

 find in it no mark of a canal at either end ; it must therefore be 

 classed with Palill'i." 



Deshayes, in his Tables, gives 7 living species of Emarginula, and 

 11 fossil (tertiary), one, E.fiuwa. an inhabitant of tho European and 



