E. Bullen Newton — Fossils from Sarawak, Borneo. 413 



Description of Shell. 

 Alectryonia amor, D'Orbigny. Knorr (Walcli) : Naturges. Verstein. 



Merkw. 1768, part 2, pi. D ii, figs. 5-7. 

 Ostracites crista-hastellatus, Schlotheim : Petrefactenkunde, 1820, 



p. 243 (name trinomial, and therefore not acceptable). 

 Ostrea colubrina, Goldfuss : Petrefacta Germanias, 1833, vol. ii, 



p. 8, pi. Ixxiv, figs. 5a-e; non Lamarck, 1819. 

 Ostrea amor, D'Orbigny : Prodrome Paleoutologie Stratigrapbique, 



1849, vol. i, p. 342. 

 Ostrea hastellata. 



Ostrea rnstellata, Quenstedt : Der Jura, 1858, p. 750, pi. xci, fig. 27. 

 Ostrea hastellata, P. de Loriol : Mem. Soc. Pal. Suisse, 1881, 



vol. viii, p. 97, pi. xiii, figs. 8, 9. 

 Ostrea (Alectryonia) hastellata, P. de Loriol : Mem. Soc. Pal. Suisse, 



1892, vol. xix, p. 346, pi. xxxvi, fig. 8 ; ibid. 1894, vol. xxi, 



p. 72, pi. ix, figs. 1-3. 

 The first systematic diagnosis of this species was furnished by 

 Goldfuss under the name of 0. colubrina as follows:—'' Ostrea testa 

 (squivahi linearilanceolata, arcnata, dorso piano lateribus abruptis, 

 plicis dorsi obliteralis lateram subacidis numerosis." 



Alectryonia amor, D'Orb. 

 Middle Oolite : Sarawak River District, Borneo. 



A. Nearly perfect upper valve (nat. size). ., ,- , i i -i 4 



B. Part of lower valve of another specimen showing longitudinal dorsal ribs and 

 grooves (nat. size). 



(Originals in the British Museum.) 



The shell is elongate, equivalve, narrow, and arcuate ; dorsal 

 area flat, with longitudinal ribs and grooves ; lateral surfaces almost 

 vertical, and bearing numerous elevated dentiform plications which 

 become somewhat hook-shaped on the dorsal margins ; inner side 

 possesses a small aliform expansion, which is covered with more 

 closely-set plications than those on the ordinary sides of the valves. 



Affinities.— Among the distinguishing characters of this shell may 

 be mentioned (1) its generally narrow form, (2) its steep vertical 

 sides, and (3) its flattened dorsal area, which is ridged and grooved 

 with elevated longitudinal ribs, the main one bifurcating after 

 a certain distance, then finally merging into smaller ramifications. 



