144 HE. F. E. COWFEE EEED ON THE FAUNA OF THE [May 1909, 



narrows rapidly ; it shows about eight or ten widely spaced, fairly 

 regular, and continuous concentric lines. In one specimen which 

 has lost the shell, the triangular axis shows faint traces of several 

 an nidations. 



Prom the characters of the head-shield we may compare this 

 species with Illcenus dalmani, Volb., 1 but the head-shield in oars 

 is rather natter posteriorly and the glabella and axial furrows much 

 shorter. The proportions of the glabella and shape and curvature 

 of the head more closely resemble I. esmarJcii, Schloth., 2 but ours 

 does not exhibit the anterior marginal fold or the strong terrace-lines 

 of this species. The shape of the free cheek and the large eye some- 

 what recall Nileus armadillo, Dalm. The pygidia which I believe 

 to belong to lllmnus weaveri are much like those of /. dalmani, 

 but the truncated corners are shorter. jSo previously described 

 British form is closely allied. Both the above-mentioned Scandi- 

 navian and Russian species occur in the Ortfioceras-Limestone. 



Ill^NTJS aff. CHTJDLEIGHEXSIS, Holm. 



In addition to the above-described new species of Illcenus from 

 the limestone, there is another small one, from the limestone-breccia 

 (45) in the upper part of Stream F, less completely known. But 

 the head-shield is very broad and short, with relatively wider fixed 

 cheeks ; and in one small free cheek which may be associated with 

 this head-shield the eye, though of somewhat similar appearance, is 

 rather oblique and rather longer, while the genal angle is not a 

 semicircular curve, but merely obtusely rounded, the lateral margin 

 being straighter and slightly excavated. As far as the foregoing 

 characters take us, this form seems allied to Illcenus chudleighensis, 

 Holm, 3 from the Cystidean Limestone of Russia. 



Pliomeea aff. fischeei (Eichw.). (PI. VI, fig. 4.) 



One imperfect pygidium of a species of Pliomera, from the lime- 

 stone-breccia (45) of the upper part of Stream F, belongs apparently 

 to an undescribed form ; but the material is too imperfect and 

 insufficient to apply to it a new specific designation at present. 

 The fragmentary pygidium is broadly transverse and almost semi- 

 circular ; but only three pleural lobes are preserved on one side and 

 two on the other, while the axis only shows five segments. The 

 anterior part of the pygidium is thus missing, though we may con- 

 jecture that its shape was much broader than that of PI. pseudo-. 

 articulala (Portl.) and more closely resembled PL actinuva (Dalm.) 

 in this respect. The portion of the axis preserved is about half the 

 length of the pygidium, and is very broadly conical, the sides being 

 inclined at about 60° and meeting at the pointed extremity ; 

 four subequal narrow simple rings (of the first there is only a trace) 



1 Holm, ' Eev. Ostbalt. Silur. Trilob.' pt. iii, Mem. Acad. Sci. St. Petersb. 

 ser. 7, vol. xxxiii, no. 8 (1886) p. 93 & pi. i, figs. 7-14. 



2 Unci. p. 47 & pi. i, figs. 1-6. 



3 Ibid. p. 101 & pi. iii, figs. 1, 3, 4. 



