84 Frederick Clia'pman : 



Observations. — This large and handsome form of the pleuroto- 

 marid group l>ears close relationship with both Phanerotrema 

 halteata, Phillips sp.,^ from the Wenlock series, and P. labrosa, J.- 

 Hall sp.,'' from the Lower Helderberg series. By the discovery of a. 

 fine, nearly complete specimen of P. rnisfralis in the Cave Hill 

 limestone by Dr. E. Brooke Nicholls, it is possil>le to add some notes 

 of interest to the original diagnosis of the less complete specimen 

 described and figured by Mr. Etheridge. 



Dimensio7is. — Height from base of columella to apex of whorls, 

 92 mm. ; greatest width of shell, 90 mm. Height of penultimate 

 whorl, 13 mm. Height of last whorl, 68 mm. Approximate width 

 of ajjerture, 55 mm. ; approximate length, 66 mm. Distance of slit- 

 band from base of shell, 50 mm. Distance of slit-band from last 

 suture, at mouth, 37 mm. Width of slit-band at mouth, 6.5 mm. 



Comjmrisons. — Body wliorl — Depressed and even slightly con- 

 cave as in P. labrosa. In P. balteata it is gently convex. Spire — 

 Moderately well developed as in P. balteata. Sutures — Deeply 

 channelled as in P. balteata. 



The Australian species appears to exceed in size any other of 

 this grouiD, and as remarked by Mr. Etheridge, is a more obliquely 

 elongated shell. 



Occurrence. — Silurian (Yeringian). In friable limestone,^ Cave 

 Hill, Lilydale. Presented by Dr. E. Brooke Nicholls. 



Fam. MURCHISONIIDAE 



Genus Coelocaulus, Oehleit. 



Amongst Silurian Murchisoiiiidae there occurs a peculiar generic 

 type of shell characterised by its turrited form, with flat whorls, 

 especially in the earlier stages, and a conspicuous, persistent 

 umbilicus. This type of shell is widely distributed, occurring in 

 various Silurian faunas of Europe, North America and Australia. 

 The slit-band is often obscure in shells of this type where the later 

 whorls are not preserved, but in specimens where the last two whorls 

 are found, the latter are subangularly convex with an infra-median 

 slit-band, and show a relationship to the genus Hormotoma, Salter, 

 as emended and typified by Mrs. Longstaff (Miss Jane Donald),* in 

 the species //. cingulata, Hisinger^ 



1 (Pleurotomnria hnlteatn). Mem. Geol. Surv. Gt. Brit., vol. ii., pt. i., 184S, p. 358, pi. xv., 

 figs, 1, 2. 



2 (Pleurotomaria labrosa). Pal. N. York, vol. ill., 1859, p. 339, pi. Ixvi., fl^'s. 1-5. 



3 This matrix is a calcareous sand composed of granules largely of algal origin, together with 

 fragments of crinoids. 



4 Quart. Journ. Geol. Soc, vol. Iv., 1899, p. 257. 



5 Turritella cinijnlata, Lethaea Svecica, 1837, p. 39, pi. xii., fig. C. 



