100 Mr. C. Lapworth on new British Graplolites. 



22. Dijj/or/r/tpfus socialis, Lapw., sp. nov. 

 (PL IV. figs. 13 a-13 e.) 



Polypary .short and stout, about otic fourth of an inch in 

 Length, with a maximum diameter of one twelfth of an inch; 

 proximal spines minute, divergent, conspicuous ; virgula capil- 

 lary, slightly prolonged distally. Hydrothecae thirty to thirty- 

 two to the inch, inclined at an angle of 45°, tubular in form, 

 without overlap; outer margin <>f each convex, with well- 

 marked proximal excavation; aperture horizontal or oblique, 

 concave, unornamented. Test transversely striated. 



The features noted above are characteristic of a highly pro- 

 lific little Diplograptua which everywhere accompanies Dicel- 

 lograptuB complanatus, Lapw., in Its extended geographical 

 range in Scotland and [reland. The Irish specimens sent me 

 by my rriend Mr. Swanston, of Belfast, are in an excellent 

 state <it' preservation, and show the superficial striation most 

 distinctly. ( >n the obverse aspect, of the polypary there is a 

 trace of a longitudinal septum, slightly undulating. On the 

 reverse aspect no trace of a Longitudinal seam is perceptible, 



the test 01 the fossil is unbroken and continuous from side to 



side The virgula, as a rule, is just perceptible, projecting 

 slightly beyond the distal margin of the polypary. 



from Diplograptua truncatus, Lapw., its most intimate 

 ally, this form is easily separated by its diminutive size, the 

 prolongation of the virgula, and some distinctions in the shape 



of the nydrothecss. 



Horizon and Locality. D. socialis occurs in countless num- 

 bers in the dark seam at the base of the "Barren Mudstone " 

 of the Moffat series at Dobb's Linn and elsewhere, upon the 

 same horizon at Coalpit Bay, Ireland, and at Shalloch Mill&c. 

 in the Girvan district of Ayrshire. 



23. Diplograptus {GhmtograptuB) euglyphus, sp. nov. 

 (PL IV. figs. Ua-Ue.) 



Diplogropbm deniable. Brongn, Lapworth, Trans. Belfast Nat. Field- 

 Olub, L866 7, pi. vi. fig. 13; Quart. Journ. GeoL Soo. 1878; Ann. 

 & Mag. Nat. I list. L879, iv. p. 424. 



Polypary diprionidian, with parallel margins, from one to 

 four inches in length, and with an average diameter of one 

 twelfth of an inch ; proximal end rounded, furnished with a 

 minute radicle, but destitute of lateral spines. Virgula con- 

 spicuous, distally prolonged. Bydrothecse eighteen to twenty- 

 lour to the inch, inclined at an angle of about 40°; short, free 

 tubes, with convex outer edge, and deeply concave apertural 

 margin. 



