16 



WEALDEN AND PURBECK FOSSIL FISHES. 





•<Vk 



Genus ASTERACANTHUS, Agassiz. 



Aderacantliu:i, L. Agassiz, Poiss. Foss., vol. iii, 1837, p. Dl. 

 Strojjhoch's, L. Agassiz, ojj. cii., vol. iii, 1838, p. 116. 

 Splienonchus, L. Agassiz, op. cii., vol. iii, 1843, p. 201 (in part). 

 Cvrtodus,^. E. Sauvage, Catal. Poiss. Form. Second. Boulonuais (Mt'm. 

 Soc. Acad. Boulogue-sur-Mer, vol. ii), 1867, p. 53. 



(jpiierio Characters. — Pi'incipal teeth elongated, irregu- 

 larly quadrate, Avitli slightly arched but flattened crown; 

 symphysial teeth few and large, much arched, Avithout 

 lateral denticles, longitudinally keeled ; all superficially 

 marked by fine reticulate wrinkles or ridges. Dorsal fin- 

 spines ornamented, by stellate tubercles, sometimes in part 

 fused into sliort longitudinal ribs; posterior denticles in t"wo 

 longitudinal series, often alternating, not marginal, l)ut 

 placed close together on a mesial ridge. One or two large 

 hook-shaped dermal S])ines, each on a triradiate base, 

 innnediately behind the orbit, at least in males. 



Ti/pe Species. — Asieracnvflivs oninfissimvs (L. Agassiz, 

 Poiss. Foss., vol. iii, 18-")7, p. ol, pi. viii), typically from 

 the Upper Jurassic of Western Europe. 



Bevjarls. — This genus is closely related to AcivJu.s and 

 Hi/h(i(Jiis, l)ut the complete fish is unknoAvn, and the teeth 

 and spines have hitherto been found associated only in a 

 variety of the type species discovered by Mr. Alfred N. Leeds 

 in the Oxford Clay of Peterborough (A. S. Woodward, Ann. 

 Mag. Nat. Hist. [(3], vol. ii, 1888, pp. 336—342, pi. xii). 

 Although dorsal fin-si)ines occur both in Wealden and in 

 Purbeck formations, no teeth have yet been met with in 

 the same horizons and localities. 



1. Asteracanthus verrucosus, Egerton. Text-fig. 7. 



1854. Asteracanthus v<rnic.osus, P. M. G. Egertou, Ann. Mag. Nat. Hist. 



PiG.7. — Asteracanthus verr^tcosus, L"J' . . , p. • • . 

 Egerton; dorsal fin-spine lack- 1855. Asteracanthus verrucosus, P. M. G. Egerton, Figs, and Descripts. 

 ingr posterior denticles, ri^lit _, . , „ ■ -n ■ /-.r n t n vi ••■ i-- 



side vie^v, two-thirds nat! size.- Brit. Organic Remains (Mem. Geol. Surv.), dec. viii, pi. u. 



.Middle Purbeck Beds: Swan- ]889. Asteracanthus verrucosus, A. S. Woodward, Catal. Foss. Fishes, 



asc, Dorset. Egerton Collection 



(B. M. no. P. 22.9). B. M., pt. i, p. 313. 



Type. — Dorsal fin-spine ; Dorset County Museum, Dorchester. 



Specific Characters. — Dorsal fin-spines attaining a maximum length of about 



