part 4] JUBASSIC CHEOyOLOGT. 433 



(B) Haselbury and Hammatoceraticls. 



In his paper on the Crewkerne district ^ Mr. Linsdall Richardson 

 reproduces W, H. Hudleston's profile ^ of the now disused quarry 

 near the church of Haselbur}^ When he was preparing his paper 

 he asked m}^ opinion as to the possible date of Bed 3 : at that time 

 I could only suggest Iradfordensis hemera, adding, however, that 

 I did not recollect any hradfordensis specimens from Haselbury. 

 Since then the possible solution of the date has occurred to me. 

 The keeled ammonites which Hudleston mentions from this Bed 3 

 are perhaps represented by the species of Hammatoceras and 

 Mrycifes, which have been obtained from Haselbury and the 

 immediate neighbourhood — H. cf. j)Ianinsigne Vacek and Erycites 

 afl:. gonionotum (Benecke) : similar forms have been figured by 

 Vacek 3 & De G-regorio^ from the strata at Cape San Vigilio, Lago 

 di Garda (Ital}'-). 



In the Bradt'ord-Abbas district occur many species of these two 

 genera^ : they have come from strata mainly dated as murcliisoncB 

 hemera, though partly or occasionally as hradfordensis. But, when 

 faunal analysis comes to be applied, it is seen that the synchroni- 

 zation of such species with murclusoncB (that is, the Ludwigoids), 

 on the one hand, or with hradfordensis (that is, Brasilia spp.), 

 on the other, becomes rather doubtful. At the Italian locality 

 are few or no species that can be properly reckoned as either 

 Ludwigoids ^ or Brasilia, but Hammatoceratids are abundant. 

 In the Hebrides the Ludwigoids are especially abundant, but the 

 Hammatoceratids are unknown. In Dorset-Somerset Ludwigoids 

 associated with the characteristic brachiopod, the so-called 

 Waldheimia anglica, are of fairly wide distribution and not 

 uncommon, but Hammatoceratids are localized and particularly 

 rare. At Haselbury both Ludwigoids and Hammatocerata are 

 rare, for the quarry was not a productive one so far as ammonites 

 are concerned ; but Hudleston notices for Bed 4 Ammonites 

 murchisonce and JVaJdheimia anglica, and for Bed 3 he records 

 keeled ammonites : evidently they were unfamiliar to him — had 

 they been of murcliisoncB or concavus (that is, hradfordensis) type, 



1 IX, 4, p. 165. 2 Yi^ p^ 41^ 



3 XL 4 lY. 5 I i^ p, 661. 



^ So far as the tiudwigoids are concerned, this statement may seem 

 particularly rash, for De Gregorio says (IV, p. 11) ' Ij' Harpoceras Murcliisonae 

 est tres-commun a S. Vigilio, et c'est une des especes les plus caracteristiques 

 de cette fanne.' This illustrates the necessity for precision in palaeontological 

 identification. The specimens which he figures (IV, pi. iii) as Harpoceras 

 murchisonx with various qualifying terms show no species agreeing strictly 

 with Ammonites murchisonse itself, possibly no Ludwigoids at all, certainly 

 not the murchisonse fauna of the Hebrides nor of Dorset-Somerset, nor of other 

 areas ; while the list of species of widely different dates which he gives as 

 possible varieties or mutations of A. '^nurcliisonae shpw how greatly outward 

 similarity may mislead. His Harpoceras m,v,rcliisonee includes a variety of 

 types, some indicative of Ancolioceras date and perhaps of earlier hemerae, some 

 more or less suggestive of hradfordensis date, some perchance indicative of 

 strata of even later dates. 



