46 ME. G. W. LAMPLUGH ON THE JUNCTIOJ^T OF [vol. Ixxviii, 



pseudojurensis Yar.' (12 specimens); ' Magas orthiformis (d'Archiac) var. 

 spiriferoides ' (about 30 specimens, besides large numbers of the normal 

 specific form and of assorted varieties ; the species, according to Walker, 

 bad not previously been found in Britain, and is rare in the Tourtia ; see 

 L. W., p. 255) ; ' Ehynchonella leightonensis var.' (3 specimens) ; ' Ehyncho- 

 Jiella cf . tripartita Pictet ' (4 specimens). 



The following (provisional) determinations are marked in pencil only. The 

 species, mostly belonging to the Tourtia, are generally represented by named 

 specimens from abroad in Walker's foreign collection, which he evidently used 

 as the primary basis for comparison. ' Terebratula cf. roemeri ' d'Archiac, 

 (many specimens) ; ' Terebratula robertoni ' d'Archiac, (many specimens : see 

 remarks on this species in L. W., p. 252); ' Zeilleria dallasiana ' (2 speci- 

 mens) ; 'Magas subconcava ' (18 specimens) ; ' Kingena leptorhabdota' (many 

 specimens) ; ' Kingena psammos ' (about 30 specimens) ; ' Aulacothyris ' 

 (several boxes) ; ' Rhynchonella nu.ciformis var.' (about 100 specimens: see 

 remarks on the species in L. W., p. 259) ; ' Rhynchonella sigma ' (3 speci- 

 mens : in a letter to me, dated January 30th, 1903, Walker wrote — ' There 

 is a curious new Rhynchonella, something like Rh. sig^na ; I shall propose the 

 name Rh. sigmoides for it.' He added : — ' The bulk of the Ehynchonellas 

 belong to the Rh. dimidiata group ; the Continental geologists lump them 

 into this species, but I think latissima should be kept separate.' His later 

 work appears to have strengthened this opinion : see (ii) above. 



A large proportion of the assorted brachiopoda in the collection, parti- 

 cularly of the Rhynchonellids, have no names on the boxes, or a generic name 

 ■only, and I know that Walker regarded some of these as probably new. His 

 attitude in dealing with the material was expressed to me concisely as 

 follows {in litt. January 16th, 1902) : — ' The difiiculty is not to describe new 

 species, but to prove that the old species are present in the bed.' Walker 

 ■defined his conception of a species in a short paper in the Geological Magazine 

 (pp. 15-17) in 1905, and from the point of view therein stated, he found that 

 the specific centres of the Shenley fossils ' where the individuals are most 

 thickly clustered and most closely resemble each other' rarely embraced the 

 individuals which were nearest the form regarded as typical for the 

 •established species of other localities ; wherefore in most cases, if an already- 

 named species had been first described from the Shenley specimens, it would 

 have had a somewhat different definition. The very numerous grouped but 

 unnamed specimens in the collection will be found usually to represent 

 Walker's ideas of the specific and varietal 'centres ' calling for recognition. 



The list of fossils other than brachiopoda given in L. W., p. 263, 

 was based on my own collection, since presented (excepting a few 

 specimens) to the Geological Survey and now preserved at the 

 Jermyn Street Museum. The non-brachiopodous material obtained 

 later by Walker, now in the Sedgwick Museum at Cambridge, 

 includes a large number of forms not already in the list ; but only 

 . some of these have as jet been identified, and it will not be possible 

 to gain a comprehensive view of the fauna until the whole 

 collection has been systematically worked through, and the fossils 

 ^compared with those from analogous deposits in France and 

 Belgium (see p. 61). The collection, however, is scanty com- 

 pared with that of the brachiopods, so that instead of the s^^ecies 

 being represented by hundreds or scores of specimens, they rarely 

 count more than units, which is to be explained partly by original 

 sparseness, imperfect preservation, and difficulty of extraction 

 (see L. W., p. 244), and partly, perhaps mainly, as the result of 

 Walker having purposely selected the brachiopoda for his chief 

 •objective. As in the case of the brachiopoda, some of the forms 



