50 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



It is evident that Professor Bronn is in error, when placing Ter. perovalis, Sowerby, as 

 a synonym of Ter. lata (see ' Index Palseontologicus'). Nor can I agree with M. D'Orbigny 

 in thinking Ter. simplex to be a synonym of T. lata (Prodrome, p. 287). 



47. Terebratula maxillata, Sow. Plate IX, figs. 1 — 9. 



Terebratula maxillata, Sow. 1825. Min. Con., p. 52, pi. 436, fig. 4. 

 — — Morris. Catalogue, 1843, p. 134. 



Morris and Dav., 1847. Annals and Mag. of Nat. Hist., 



pi. xix, fig. 5. 

 D'Orb. 1849. Prodrome, vol. i, p. 287. 



Diagnosis. Shell subquadrangular, as broad as long, valves nearly equally convex, 

 beak produced, narrow, and strongly recurved ; foramen large, oblique ; deltidium obtusely 

 triangular; cardinal area slightly depressed, with obtuse lateral ridges; imperforated 

 valve with a mesial sinus, and two lateral ones corresponding to the lobes of the perforated 

 one, and which only extends one third inwards from the margin ; front strongly sinuated 

 in the young state, while for a considerable period of growth, no trace of sinuated margin 

 is perceptible. Loop attached only to crura, extending to little more than one third of the 

 length of valves. Length 32, breadth 34, depth 18 lines. 



06s. This is a very variable shell both in form and size, it is well described by Sowerby 

 in 'M.C.,' who states it to be "distinguished from Ter. intermedia by the depth of the 

 sinuses and consequent furrows which extended at least half way to the beak, in some 

 specimens the two ridges between the furrows are very prominent and approach more 

 nearly together, than in the specimens figured ; such shells are generally long shaped, 

 &c." This species has been found to attain in some localities much larger dimensions than 

 those observed by Sowerby, who states it to be " always smaller than Ter. intermedia." 

 In the 'Annals and Mag. of Nat. Hist.,' October 1847, Mr. Morris and myself had occasion 

 to notice some large specimens of this species found at Pickwick, which are figured in 

 Plate XIX of that periodical. Since that period, still larger specimens have been procured, 

 as may be seen in the Collection of the British Museum (Plate IX, fig. 4) ; and we have 

 been able to trace every size in this species, from that of a pin's head to the larger specimens 

 just mentioned ; its greatest diameter is sometimes in the longitudinal, at other times in 

 the transverse direction ; some varieties are with the same dimensions deeply plicated, 

 while others show no traces ; in the young state, and for a considerable period of growth, 

 there is no indication of plication, as may be seen by a glance at Plate IX, where we have 

 illustrated all these different states ; fig. 1 is the original form, considered by Sowerby as the 

 type of the species. Ter. maxillata is abundantly distributed throughout the Forest Marble, 

 the Bradford Clay, and the great Oolite round Bath, near Sapperton, and Hailey Wood, 

 about Cirencester, &c. ; large specimens were found on the Continent, at Boulonge-sur-mer, 

 by M. Bouchard. Professor Bronn, in his 'Index Palaeontologicus/ considers, erroneously, 

 this species a synonym of Ter. biplicata, thus placing together, under one head, a number 



