28 FOSSIL CIRRIPEDIA- 
SqmepEtauM MAXIMUM, var. typicum. Tab. II, figs. 1, 4, 5, 8. 2 
S. carind introrsim leviter arcuatd, latitudine valve altitudinem superante ; tecto 
transverse leniter arcuato; parietibus intra-parietibusque angustis, superficie pane 
levi. } 
Carina slightly bowed inwards; width of valve greater than the depth; tectum flatly 
arched transversely ; parietes and intra-parietes narrow ; surface nearly smooth. 
Carina, Tab. II, fig. 1. In this, the typical variety, the carma is very slightly bowed 
inwards, widening gradually downwards from the apex, of which no part projected freely ; 
walls rather thin; tectum very flatly arched, not sub-carinated ; basal margin rectangu- 
larly or rather more acutely pointed; parietes very slightly concave, splaymg outwards, 
narrower than one side of the tectum, separated from it and from the intra-parietes by 
rounded ridges ; intra-parietes narrow, not extending baseward so far as the basal margin 
of the parietes ; width of valve measured from marginal edge to edge, considerably greater 
than the depth, measured in the same place from the central crest to either marginal edge ; 
but the width compared with the depth varies a little: imner margin of valve nearly 
straight. Length of longest specimen (JZws. Fitch) nearly 13 inch. ‘This variety in the 
Norwich beds seems about equally common with var. su/catum, but the former alone is 
found in Hanover and in Scania, excepting that in the latter country some specimens indi- 
cate a passage to the var. eylindraceum. 
Scutum, Tab. II, fig. 8. In Mr. Fitch’s collection there are three left-hand valves of a 
Scalpellum, which, from their size and smoothness, I have no doubt belonged to this species, 
and from their thinness, probably to the variety of carina considered as typical under the 
simple name of S. maximum: valve unusually thin and little convex; trapezoidal, with 
the apex less produced than is usual in the genus; broad in proportion to its length, the 
basal margin being ‘66, and the occludent margin ‘98 in length, therefore the breadth 
equals two thirds of the length. Basal margin (just perceptibly hollowed out) forming less 
than a right angle with the (just perceptibly outwardly arched) occludent margin, and 
forming an almost exact rectangle with the lateral margin; the latter meets the tergal 
margin at an angle of about 135°. The edge of the tergal margin is thickened and 
slightly reflexed ; the upper part of the lateral margin is in some specimens a little bowed 
inwards. The baso-lateral angle is rounded and just perceptibly protuberant; no ridge 
or furrow runs from it to the apex. Internally the depression for the adductor muscle is 
singularly shallow (fig. 8c); a very small portion of the upper part of the valve projected 
freely ; the internal surface of the valve, above the pit for the adductor muscle, has not 
been thickened, and is therefore slightly concave or almost flat. The internal occludent 
edge in the upper part is only a very little widened, and is flat; on the tergal margin, 

