498 CAMBRIAN BRACHIOPODA. 



same general character as that of Lingulella radula Matthew and Lingulella mariinensis 

 Matthew. It is exceedingly fine and is discernible only with a strong magnifier. 



The surface of a specimen represented by Plate LXIX, figure It, is marked, in addition 

 to the radiating and concentric lines, by irregular, more or less transverse lines that suggest 

 the surface of species referred to the subgenus Westonia. Associated specimens do not show 

 tlois peculiarity of surface. 



The interior of the dorsal valve is not well shown. In two specimens (PI. XXIX, figs. 1 

 and 1 1) traces of the visceral area are preserved, and the area and pedicle groove are indicated 

 in figure If. In the casts of the dorsal valve the area is clearly defiiied (fig. In) and the trans- 

 median (i) and the central muscle scars (h) (fig. Iq). The main trunk of the vascular sinus 

 is far out toward the margins (fig. Ir), and in the same interior the paths of advance of the 

 muscle scars are imusually prominent. A median sinus appears to be indicated in figure In. 



Observations. — ^Through the courtesy of Dr. Gilbert D. Harris I have been able to com- 

 pare the type specimen of "Lingula ? dawsoni," which belongs to the Hartt collection of Cornell 

 University, with the specimens referred to the species by Matthew. Only one of Matthew's 

 specimens [1886, PI. V, fig. 9d] belongs to the species. Two other specimens, however, described 

 and figured as " Lingulella linguloides" [Matthew, 1886, p. 34], are undoubtedly specifically iden- 

 tical with the original type of " Lingula f dawsoni," Matthew's identification being based on the 

 figure of the specimen described and illustrated by me [1884a, p. 15]. 



Two other specimens illustrated by Matthew [1886, PI. V, figs. 9, 9a-c] as " Lingulella 

 dawsoni" appear to be identical with L. maftinensis Matthew. Both the ventral and dorsal 

 valves of the two figured specimens are broken away at the beak, and allowance is also made 

 for their being compressed in shale, while the types of L. martinensis are embedded in sandstone. 



It will be noticed that our Plate XXIX, figure 1, differs from Matthew's figure 9d [1886, 

 PI. V] in the form of the visceral area, although they are drawn from the same specimen. The 

 shell is small, and the markings are somewhat indistinct, but from what may be seen and 

 from our knowledge of the form of the markings in the closely related species, I think the change 

 in the figure is necessary. 



A shell that appears to be identical with tliis species occurs in the compact, gray, thin- 

 bedded sandstones that are interbedded in the Upper Cambrian shales on McNeil Brook, 

 1.5 miles (0.94 km.) east of Marion Bridge, Cape Breton, Nova Scotia. The species is abun- 

 dantly represented, the partings of the shaly sandstone often being nearly covered with the 

 detached valves. The average length of the ventral valve is 3 nam. 



Lingulella ferruginea occurs in abundance m the shales and interbedded limestones of the 

 Manuels Brook section, Newfoundland, and also in the dark shales above the Lower Cambrian 

 beds near Topsail Head, on the shore of Conception Bay. In order to exliibit the range of 

 variation caused by the character of the embedding matrix, a number of specimens are illus- 

 trated. Plate XXIX, figures le to Ik, and In, are from the shales; figures If, li, Ij, and Ik 

 show the effect of compression and distortion, while figures 1 1, Im, lo, Ip, and Iq, from the 

 limestone, are more convex and regular, although the specimens they represent were chosen 

 as illustrating variation in form. 



In the Manuels Brook section, Newfoundland, Lingulella ferruginea is associated with 

 Acrotreta misera, Agnostus punctuosus, Microdiscus punctatus, Paradoxides davidis, P. Mclcsi, 

 Anopolenus venustus, Conocoryphe elegans, CtenocepJialus matthewi, Erinnys venulosa, Ptycho- 

 paria robli, P. variolaris, Holocephalina inflata, Agraulos socialis, etc. [Walcott, 1891b, p. 261]. 



Davidson [1868, p. 306] gives a Ust of the fossils that occur in association with Lingulella 

 ferruginea in the Menevian group of Wales. x\jnong them we find Paradoxides davidis, P. 

 hicJcsi, Erinnys venulosa, Ptychoparia variolaris; also the genera Holocephalina and Anopolenus. 



The above-mentioned association of species in the Newfoundland and Welsh beds shows 

 that Lingulella ferruginea occurs in the same relative faunal horizon on the two sides of the 

 Atlantic. A comparison of the illustrations of the type specimens [Salter and Hicks, 1867, 

 figs. 1-3] and those subsequently described and illustrated by Davidson [1871, PI. XLIX, figs. 

 33 and 35] shows clearly that there are no true specific differences between the two species. 



