270 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



in which the corallites are everywhere surrounded by hard compact dolo- 

 mite, though their interior is quite free from the matrix. The .specimens 

 present good longitudinal and transverse sections of tlie corallites, which 

 show the internal structure of the latter admirably, but the surface mark- 

 ings of the corallites are nowhere visiljle, and the exact mode of growth 

 of thp whole corallum is uncertain. 



This species differs from the typical furms of (,'<il mniiitrit^ in its cylin- 

 drical, separate, and probal)ly fasciculated corallites, and Ijelongs to an 

 aliei-rant section of that genus, for which I>yhowski has proposed the name 

 (_'ijittliiii}]iifllii'iili-s. It is clearly congpiieric, and niay even pro\'c to be 

 conspecific, with the (' ijnthiiiilnjlloidiiK RJifiuniiiiii. of Freeh, from the Devo- 

 nian rocks (if the Eifel, which Dr. Freeh informs the pi'cscnt writer is 

 also a Ciil niiiniirtii. ^Vround Lakes ^Manitoba and A\'innip<'gosis, tocj, C. 

 ilisj/i'ui-fa has, so far, been found invariably ass(jciated with Sfriiii/in'i'/i/ni- 

 /lis- /liir/i'Hi, as C Rhi'iiannin. is at PaftVath. 



(S.) Amplexus, or DipiivpiivllujM. (>Sp.) 



Plate :)r>, figH. -2 aii.l ii. 



A nuni))cr of fi-igmentary specimens of a species of /I ;;/y</c.f'«,s', I'i/cikisIij- 

 Ins or IMjilniplnjII mil were collected Ijy Mi-. l»owling in ISSi), on the west- 

 ein shore of Dawson Bay, on two small jjoints, one two miles and a half 

 and the other four miles and a half north of tlie mouth of the Jtdd Deer 

 Iiiver. These specimens do not show conclusively whetliin- the entire 

 corallum was <jrigin;i,lly composite or simple, the surface markings are 

 unknown, as arc also the characters of the calyces. <Jn the other hand, 

 the internal structui'e of the corallites (or corallum) is well preserved and 

 clearly shown in numerous natural sections. The specimens consist of 

 straight or llexuous cylindrical tubes, which average about fi\i'. millimetres 

 in leiigth, are imperfect at both ends and indjcdded in compact or \esicular 

 dolomite. The interior of these tubes is comprised of a veiy narrow outer 

 or ].)ciipheral and septate zone and of a broad central tabulate area. The 

 oulei- zone appears to be Ijounded internally by an inner wall. The 

 septa, which are equal in length and thiity twcj in nundn^r, all exteiul 

 fr(jm the outer to the supposed innei- wall, and terminate on the inner 

 surface of the latter, in some cases as continuous and sHgiitly raised lon- 

 gitudinal ridges, in others as linear rows of minute tubercles, both modifi- 

 cations being observable in the same tube. Tlie iiiterscp(,n,l spac<'s lietween 

 the (juter and inner wall are traversed l)y small dissepiments. In the 

 central tabulate area, which occupies about four fifths of the entire dia- 

 meter, the tabulic are for the most part llexuous and irregular in Iheir 

 shape and disposition, the distances between them varying from jialf a 



