78 Frederick Chapman : 



riblets, which extend over the edge of the lamellae where well 

 preserved. 



Dimensions. — Length, 20 mm. Approximate width when com- 

 plete, 15.5 nan. Greatest height from ventrum to dorsum, 10 mm. 



Observations. — This distinct species is easily separated from the 

 earlier named Victorian form, //. nycteis, in the more spacious 

 ■concentric ornament, its lamellate character, and in the more 

 •evenly rounded dorsum. 



H. elegantulum is closely allied to //. em/«e?«s, Barrande sp.l 

 from the Lower Devonian (Etage F), Konieprus, Bohemia. It 

 ■differs from that species in having a more narrowly ovate and 

 liigher shell, and agrees in the lamellate and radial ornament. 



Occurrence. — Silurian (Yeringian). In limestone, Cave Hill, 

 Lilydale. Holotype presented by Mr. J. S. Green. 



Fam. Cyrtolitidae. 



Genus Temnodlscus, Kokt^n, 1896. 



Teinnodiscus pharet7-oides, .sp. nov. (Plate., XL, Figs. 4, 5; Plate VI., 

 Figs. 50, 51). 



Description. — The Victorian specimen is in the form of a cast. 

 It shows the compressed initial coil with rapidly widening body- 

 whorl. The latter is expanded on the inner side. The slit-band is 

 keel-shaped and prominent, and the surface of the shell is 

 •ornamented with concentric rugae. 



Dimensions. — Diameter, 8 mm.; width of last whorl, 6.5 mm.; 

 -width of mouth, 8 mm. 



Ohservatiojis. — In form this species resembles Lindstrom's 

 '" Cyrtolites'' pharetra,"^ of the Silurian of Gotland, with the 

 -exception that the Victorian species is wider across the mouth at 

 the inner part of the body whorl, its keel is sharper and more 

 :salient, and the concentric ornament more rugose. 



Another somewhat allied species is Perner's Temnodiscus ferri- 

 gena,^ fi'om which the Victorian species differ in the greater 

 umbilical diameter and the more discoidal outline. The ornament 

 in the Bohemian species consists of finely striate growth-lines, as 



1 Perner, in Barrande's S.vst. Sil. Boht'me, vol. iv., tome i., 19C3, p. 37; tome ii., 1907, pi. civ., 

 fisrs. 13-15 and fig. 10 in text. 



2 Kongl. Svenska Vet.-Akad. Handl., Bd. xix., No. 6, 1884, p. 8:^, pi. vi., fi'jfs. 39-51. 



NoTK.— Some of Lindstrlim's species referred to Ci/rtn[ites: properly belong to Oxi/discus, as 

 pointed out by Koken— Bull. Acad. Imp. Sei. St. Petersb., ser. v., vol. vii., 1897. 



3. In Barrande's Syst. Sil. Boiieme. vol. iv., tome i., 1903, p. 78, fig. 51 in text; tome ii,, 1907. 

 pi. c-xiv., figs. 5, a. 



