458 ME. H. BOLTOX ON A MAEINE FAUNA IN THE [NOV. I907, 



Chonetes sp. (PL XXX : figs. 1 & 2 are syntypes, fig. 3 a 

 variety.) 



Compare the following figures and descriptions : — 



Chonetes hardrensis, Phill. emend. M'Ooy (who omits Devonian forms); 



M'Coy, ' Brit. Palseoz. Foss.' 1851-55, p. 454. 

 Ch. variolata (d'Orb.), interpreted by de Eoninck, 1847, ' Monographic du 



Grenre Chonetes' in 'Becherches sur les Animaux Fossiles' pt. i, 



p. 206 & pi. xx, figs. 2 a-2c. 

 Ch. hardrensis, Phillips ; Davidson, ' Monogr. Carb. Brach.' Palaeont. Soc. 



(1858-63) pi. xlvii, fig. 22. 

 Ch. tuberculata (M'Coy), ' Synopsis Carb. Foss. Ireland' 1862, pi. xx, fig. 5. 

 Ch. aff. Laguessiaiia, de Koninck ; Wheelton Hind, Quart. Journ. Greol. 



Soc. vol. lxi (1905) pi. xxxv, fig. 4. 



Description of Pedicle-Valve (figs. 1 & 2). 



Periphery trapezoidal to nearly rectangular; width 1| times the 

 length, cardinal line usually produced into short ears. 



Surface-curvature. — Medial area flattened or slightly sulcate, 

 strongly raised, and conspicuously bounded by broad, slightly-concave 

 slopes, which merge by continuous curvature into the flattened 

 wing-areas. 



Ribs sharp and well spaced, irregularly intercalated and forked, 

 indistinct on the wing-areas. Cardinal spines : five or six on each 

 side. 



' Pits ' relatively large and well spaced, when compared with 

 those of a papilionaceous Chonetes. 



A few varioles are dispersed over the ribs, especially near the 

 anterior margin. 



Dimensions small ; the average width does not exceed 10 mm. 



A variety (fig. 3) has more closely-approximate ribs and more 

 prominent ears. 



Resemblances and differences. — Chonetes hardrensis,, 

 Phill., Dav. (loc. jam cit.), is very close to our form, but appears 

 to lack the flattening or sulcation of the medial area. Davidson's 

 figured specimen was derived from the shales above the Hosie 

 Limestone (Cyathaatonia-Zone). 



Chonetes variolata, de Kon. (op. jam cit.), agrees very closely with 

 our form ; but the enlargement of the test-ornament, shown in 

 de Koninck's fig. 2 b, indicates much less pronounced furrows and 

 a much greater number of varioles on the ribs. 



Chonetes tuberculatus (M'Coy) is a bigger, longer, and less 

 parallel-sided form with coarse and more regular ribbing. 



Chonetes aff. Laguessiana, figured by Dr. Wheelton Hind from the 

 Coal-Measures of North Staffordshire, is very similar, but a bigger 

 shell and more uniformly ribbed. 



Chonetes crassistria (M'Coy), ' Syn. Carb. Foss. Ireland ' 1844-62, 

 pi. xx, fig. 10, is quite distinct. This species has a small number 

 of simple strong ribs, and was no doubt correctly assigned to 

 Ch. Buchiana, de Koninck, by Davidson. 1 



1 The figure given in the ' Synopsis ' is incorrectly drawn, and the species was 

 re-figured by M'Coy in the 'Brit. Palseoz. Foss.' 1851-55, pi. iiin, fig. 5. 



