88 Mr. T. R. Jones on Scandinavian Beyrichia!. 



3. Beyrichia Dalmaniana, iiov. sp. PI. V. fig. 13. 



Anterior extremity of valve contracted, so as to give an almost 

 triangular outline. Surface bearing five smooth rounded un- 

 equal protuberances or lobes ; two obliquely placed anteriorly, 

 two posteriorly, and one in the middle towards the dorsal border ; 

 the infero-posterior lobe is the largest. In the arrangement of 

 these five lobes some reference to that of the ridges in the pre- 

 ceding species can be recognized, the two anterior lobes being 

 the equivalents of the divided cephalic ridge in B. tuber culata ; 

 the posterior lobes representing the great caudal ridge, and the 

 central lobe being isolated and similarly placed in both species. 

 The narrow depressed border of the valve is slight but distinct. 

 The surface is smooth, with traces of very fine linear punc- 

 tations. 



Only a right and a left valve were found (in No. 3. lime- 

 stone). 



I have distinguished this rare and curious little Scandinavian 

 Beyrichia by the well-known name of one of the illustrious 

 palaeontologists of Sweden. 



4. Beyrichia Maccoyiana, nov. sp. PL V. fig. 14. 



Carapace-valve nearly semicircular ; bearing three almost sym- 

 metrical rounded ridges. The anterior ridge broad, tapering 

 downwards and backwards, and disunited at its termination from 

 the others by a very slight depression. The middle ridge oval> 

 united below with the posterior ridge, but constricted at the 

 junction ; the two forming a compressed horse-shoe ridge. Sur- 

 face of valve punctate. The marginal depressed rim is broad, 

 prominent, and trenchant, especially on the ventral margin, 

 where it is marked by regularly placed, transverse, depressed 

 lines or strise equally on its upper and its under surface. This 

 breadth of the ventral rim gives rise to the peculiar semicircular 

 form of the valve. 



The surface-lobes of this species have the arrangement of 

 those in B, Buchiana ; but, the furrows not being so deeply ex- 

 cavated, the ridges are fuller and less distinctly separate. The 

 punctation of the surface and especially the well-developed and 

 striated rim are the peculiar characteristics of this species. 



B. Maccoyiana approaches some of Prof. HalFs* figures of 

 B, lata (Vanuxem sp.), a Beyrichia from the Clinton rocks of the 

 U.S. ; but differences in the relative proportions of the ridges, 

 and especially the broad rim, sufiiciently separate the two forms. 



Three specimens of left valves are all that I have found (one 



y * PalsEontology of New York, vol. ii. pi. A. Cy6. fig. 10. 



