45 



lower m;irgiii, Imw^ bt-iit i!|)\v;ii(ls, auil (ibtn.^L'ly imiiito.l. As foi- ilir s\ii.i!ivm.=!, 

 I ii'lur to Lisiliki". ' 



Tlio slid! being vlmv coininoii at Tol<iu, it is indeed strikiiij; th it it is so 

 rarely met ^with at Onuiri. 



Tiie specimens deseribed by Morse a.s having an uimsnally broad liinge area are 

 possibly exceptiotmally dcvelop-.'d ; the Oji-s[)eciinens do not dilFer from tin.' living. 



Aira mhcrenata Lisclike. 



(Japan. Meeres-Coneh. vol. I. p. 14t;, pi. {), f. 1-3, and vol. II, p. 144.— 

 Moi-se, shell-monnd of" Omori, p. 2').). 

 Of tins species (dilfering from tlic foregoing by a much smaller number 

 of ribs, viz. 30 to 33, instead of iibout 42, by their ercnulation and by the eha- 

 raetors of the sub-genus S<.':ip]iarea!, some small specimens have been fonml at (T|i 

 which perfectly agree with Li.schlce's diagnosis and figure and with recent speri- 

 uiens. They are neither nunierüus nor large enotigh to allow any remarks about 

 deviations from tlie Oiuori or recent form, like those described by IMorse. 



I'cituiiculus (jlijcimcih Lirme. PI. VI, I', "iii. 



(Sy.st. nat. ed. 12, p. 1143. .us Area — Forbes ami llauley. lait, Moll. vol. 

 2, [.. 24."), 1.1. 4G, f. 4-7.— JelTreys, brit. Couch, vol. 2, p. ICC.-Wein- 

 k.iuli'. Conch, d. Mittulin. vol. I, p. 1S3.— Wood, Crag Moll. II, p. CO, 

 pi. !>. f. 1, and second Suppl. p. 43, pi. G, f. f).— fx-hrenck, Moll, des 

 Ainurlandes n. Nord-.lapaiis, p. 580. — Syu. I', nummariuslirocchi, conrh. 

 foss. .subap. p. 483, ]il. 2. f. 8, auctore R. Wood. — ISyn. also J', pilosus? 

 Liniie, Laman^k, hist. nat. vol. G, 1. }). 41), No. 2, riiilippi, Kn. Couch. 

 Sic. vol. 2, p. 44, and vol. I, p. 62.— Syn. also T. variabilis Nyst. Cocp 

 foss.lK-lg. Vol. 2, p. 2 and 9, pi. 20, f. 1.— Syn. also' P. albo-lineatus 

 Uschke. .Japan. Meercs-Conch. vol. Ill, p. 108, pi. !), f. 11 and 12.). 



Authors generally unite' tl\e two Linn;e,m siX3cies, whilst Weinkauff gives 

 like IJorn the name P. pilosus to the P. bimaculitus of Poll. He also ex- 

 cludes the P. insubiicus lirocchi, which is united to P. glycimcris by some, 

 and gives that name to the species better known under the Lsimarckiin name 

 of P. violosccii.s or violacesccns. — 'J'he bc^st list of .«ynonyma is geui'r.illy said 

 to be tliat of S. Wood. 1. c, to which I athl only the P. allHiliiitatus of 

 Lisclike, a.s I could not lind .uiy constant differences between the Ja|)ane.se and 

 I"',uro)H.'an specimcu.s. At all events, the punctures on which T-ischke l.iys soiu^» 

 stre.s.s are to U' .sch-u in most of the Oji sixvimens, and, at the.H;iine tiini-, th'-y do 

 not dilVer from what is sei-u in many of the MunnK^^an .shells of tliis s|H'cies. .\s 

 for tin- coloring, it i.s known to lie variable in P. glycimcris, and i\n' uhitr 

 r.idiating lines cm scarcely lie of any iini)orfance in a shell which h.is radial ribs. 



The s|Mfim('ns found at t).ji are— like all th-- fossil s)iecimens of (he olhcr 

 looalitiifl to be menlioned— mostly small, widotn exceeding .OO mm. in length, 4S 

 in height, and 30 in tliickmss. Tin y iH-long to the transverse or circular variety, 

 not to the elongated one. Their nunilfcr is, though decidedly inferior to the 



