ON THE FOSSIL PJIYLLOPODA OF THE TAL-EOZOIC ROCKSl 



77 



centric lines of growth, and, in some cases, in the delicate surface orna> 

 ment between them. 



Another objection to the supposed Aj)tychus nature of many of these 

 circular and ovate shields arises from the fact that they were not origi- 

 nally flat discs or plates, as may be seen by examining a series from 

 various localities. 



Thus Discinocaris Browniava was in some degree convex, with a 

 low conical apex ; Asj)!iIocaris triaslca was evidently conical, as may 

 be seen by the split state of the outer rim, caused by the flatten- 

 ing of the whole shield ; others, as Spatldocaris EmerKonii. and 

 Itii^gocaris Luthrri had e]e\'ated subconical carapaces. Apfi/ch()2)s{s not 

 unfrequently exempiiSes the same condition and similav breakage. A 

 median mark, caused by the depression of the central portion in 

 Cardiocaris hipnrtiia and 0. Korrieju, is also the result of flattening in a 

 toughish subconical shield. Again, some of these carapaces were bent 

 like a low ridge along the dorsum, as shown by Mr. J. M. Clarke's de- 

 scription and figui'e of Dipterocaris i^vocne — all which conditions are com- 

 patible with the nature of Phyllopods. 



as 



rhijllo2]odoiis Shields figured hy earhj observers (1S32-1850). 



1. 1832-48. — One of the above-mentioned little fossils has been re- 

 corded as ' Aph/chus hvvigatus (Goldfuss) ' in von Uechen's German 

 Iranslation of De la Beche's ' Manual of Geology,' ' Handbuch der 

 Geognosic,' 1832, p. 529 ; and it was entered in Bronn's ' Index 

 Palajontologicua,' 1848, vol. i. p. 00. As we know of no figure, we cannot 

 ofl'cr an opinion as to its generic relationship. 



2. 1842. — The ' Aptijckas vctvstus ' of d'Archiac and de Verneuil, 

 ' Transactions Geol. Soc. London,' ser. 2, vol. vi. 1842, p. 343, pi. 2G, f. 

 i\ found in the Devonian beds of the Eifel (rare), is one of these little 

 apparently bivalved but really tripartite carapaces, with a front notch, 

 and an open split at the hinder part of the median suture. If this latter 

 feature be an original condition, as it seems, the species is referable to 

 Dlpterocaris. 



3. 1846. — In 1840 A. von Keyserling gave figures and descriptions of 

 some small Aptychns-like fossils in the ' Wissenchaft. Beobacht. Pets- 

 chora-Land, Geogn. Beobacht.' p. 286, pi. 13, f. 3-7. These he referred 

 to as being probably the Aptychi of Goniatites. The figures show no median 

 line of suture; and therefore, instead of looking like the more common 

 Aptychopsis, they resemble the allied Discinocaris, with an undivided shield, 

 and with a rounded or elliptical nuchal or cephalic notch. If this latter 

 feature be real, we have a form here which comes near Ellipsocaris. One of 

 his figures in particular (fig. 3) reminds us of this genus.' 



4. 1850.— In the * Paloeontographica,' vol. iii. p. 28, pi. 4, fig. 18, 

 P. A. Roemer described and figured his Apfychus duhiiis, from the Upper 

 Devonian beds of the Hartz (Goniatite-limestone of the Kelwasserthal), 

 M. Barrande in 1872 was inclined to refer it to Aptychopsis (' Syst, Sil. 

 Boheme,' vol. i. Snppl. p. 450) ; Mr. J. M. Clarke thought it might be a 

 iSpathiocaris ; but we regard it as a Discinocaris. 



5. 1850. — In the same volume of the 'Paloeontographica,' iii. p. 88, 

 t. 13, f. 13, F. A. Romer also illustrated what he regarded as an Aptychva 



' We are informed tliat unfortunately these Russian specimens cannot now bo 

 found ut ISt. retorsburg. 



