28 SUPPLEMENTARY APPENDIX. 



Family— TEREBRATULID^l. 

 Sub-Genus? Zellania, Moore, 1854. 1 

 Type. Zellania Bavidsoni, Moore. 



Diagnosis. — Shell minute, with a small area in each valve ; foramen large, and more or less circular, 

 encroaching on both valves ; hinge articulating by the means of teeth and sockets ; valves convex, dorsal 

 one usually most so ; external surface rugose, showing a slight tendency to striation, or marked by 

 concentric lines of growth, which appear more defined on the ventral than on the dorsal valve ; ventral 

 valve having sometimes a slightly produced beak. Interior of dorsal valve showing a flattened granulated 

 margin, surrounded by an elevated ridge, which, commencing immediately under the dental sockets, 

 passes to front of the valve, and is there united by a central septum. 



Obs. These shells approach in their exterior form to Morrisia, having the large and rounded 

 foramen encroaching on both valves as in that sub-genus. Their internal character, however, shows that they 

 have affinities with Argiope and Thecidium, and will consequently link more closely the Terebratulidce to the 

 Thecideidce? This genus is not uncommon, being represented in the Upper Lias by one, and in the Inferior 

 Oolite by two species. 



Family.— SPIRIFERIDiE. 



Sub-Genus? Suessia, E. Beslong champs, 1854. 3 

 Type — Suessia Costata, E. Deslongchamps. 



Among the many new forms of Brachiopoda lately discovered by Mr. E. Deslongchamps in the Upper 

 Liasic beds of May, near Caen (France), were two species of Spiriferida, which appeared to him to possess 

 characters sufficiently distinct from the other sections in the family, to admit the propriety of creating for 

 their reception a separate section or group, to which he has applied the name Suessia. I am unprepared 

 to offer a positive opinion as to the value of this section, not having yet been able to study examples 

 sufficiently perfect. All we at present know of its characters have been described and illustrated by the 

 distinguished French author. 



In general external contour and aspect, the two species of Suessia at present known (S. costata and 

 »S. imbricata) differ but little from certain forms of Spiriferina, such as Sp. Miinsteri, &c. ; but while in 

 this last the shell structure is perforated, it is said to be impunctate in Suessia. 



The interior of the dorsal valve is still imperfectly known. Between the sockets may be seen a small 

 trilobed cardinal process (to which were fixed the cardinal muscles) ; the hinge plate is largely developed, 

 extending to about a little more than a third of the length and breadth of the valve, deeply notched in 

 front. It is formed of two concave plates, united longitudinally under the cardinal process. On these plates 

 are seen the four grooved depressions for the insertion of the pedicle muscles, the lateral ones being by far 

 the largest. At the base of the sockets the hinge-plate presents a peculiar (hook-shaped) incurved process ; 

 from the base of each plate the lamellae forming the first coil of the spire proceed, and are directed towards 

 the front ; but before becoming spirally reflected, each lamella is united towards the centre of the valve 

 by a transversal lamellar process, in the shape of a T (the spire is still unknown). The quadruple im- 

 pressions of the adductor seem to be placed as in other Spirifers, and separated by a slight 

 longitudinal ridge. 



1 This description was obligingly communicated by Mr. Moore, and will be found published, with 

 figures, in the 5th volume of the Somerset Archaeological and Natural History Society for 1854. 



2 Refer to Mr. E. Deslongchamps' able memoir, now publishing in the 10th volume of the * Transactions 

 of the Linnean Society of Normandy,' 1855. 



3 'Annuaire de l'lnstitute des Provinces,' for 1854. Named after the distinguished Viennese 

 author, M. Suess. 



