128 R.M.Brydone — Further Notes on the Trimmingham Chalk.. 



GiRRHIPEDlA. 



Add Tollicipes faUax, Darw. (very abuudaut) . 



Substitute Brachylepas cretaceus, H. "Woodw., for PoUicipcs cancellatns, wbich has 

 proved to be a synonym. 



POLVZOA. 



Add Siphoniotyphhis tennis, Hag., a species of remarkable range for one so specialised. 

 Lamellibranchiata. 



Add Avicula cmrulescens, Nilss. ; Ostrea canaliculata, Sow. ; 0. hiaquicostata, 

 S. "Woodw. — if the Trimmingham specimens are rightly identified, this 

 species can hardly be identical with O. scmiplana, as suggested in the recent 

 Survey Memoir ; Plicatula sigillina, S. P. Woodw. ; Spondylus spinosus, Sow. 



Correct Diccras incequirostratus in Survey Memoir. This record appears to be 

 founded on adherent valves of an Exogyra so identified at South Kensington. 



Gasteropoda. 

 Add DentaUum sp. There frequently occur casts of Gasteropods, mainly Troehus^ 

 and Cerithiitm,h\ii so small and delicate as to require an expert to identify them. 



Cephalopoda. 

 Add Bayjicldi, F. & C, after Nmitiliis. 

 Substitute Aptyclms rugosus, Sharpe, for A. peramphts. 



Omit Belemnitella sp. Dr. Blackmore is convinced that the very numerous specimens' 

 of this slender form are only young B. mucronata, the infant mortality among 

 which must have been terrible. 



Pisces. 

 Add CccIorJtynchus cretaceus, Dix ; Corax s]). ; Scaphanorhync/ii(s snbitlatus, Ag. 



It will, perhaps, be well to comment on some statements 

 made by Dr. Eowe in his paper on the Dorset Chalk, in which 

 he compares the fauna of the B. mucronata zone in Dorset and 

 Norfolk, as they are calculated to mislead anyone having only 

 a slight knowledge of the Trimmingham fauna. He states that 

 Peden concentriciis is common at Trimmingham. As I have never 

 seen a specimen of it there, I can only conclude that he is confusing 

 the smooth Fecten Nilssoni (which is common at Trimmingham) 

 with F. concentriciis. He also states that a certain hexagonal Serpida 

 was considered by me to be S. difformis, but that it differed from the 

 Trimmingham examples, " which are always pentagonal." He has 

 here confused at least three perfectly distinct species. The first is 

 a free-growing, tapering, uniformly heptagonal form of carious surface, 

 which is either S. difformis or a very near relation. This form, or 

 one barely separable from it, occurs also in the £. mucronata chalk 

 of Hampshire down to its base. The second is a very remarkable 

 form with a polished surface. It starts with a broad base and 

 triangular cross-section with a strong dorsal carina, and is then 

 incapable of being separated from S. macropus. But very soon the 

 tube rises free from the base and proceeds to develop six more carinte 

 placed at regular intervals round the tube. But the new carinas are 

 not all developed at once, and the specimen forwarded to me by 

 Dr. Eowe for identification was, if I remember rightly, a youngish 

 specimen with six cariuse fully developed and the seventh just 

 appearing. This form is not uncommon in the B. mucronata chalk 

 of Hampshire, but I have not yet found it (at any rate, to be certain 

 of it) at Trimmingham. At the time I saw Dr. Eowe's specimen 

 I was still under the impression that this form would prove to be 



