314 The American Geologist. Novombcr, i899 
and Rathbun (E). The genus Plcurotomaria is represented by one 
peculiar species, PI. rochana H. et R (E). A Bellerophon (B. steltz.- 
neri) was brought from the Rio Curua and is described together with 
the similar B. morganianus H. et R. from Erere. A Bucania (B. freit- 
asi M) which has the proportions and probably the exterior of the B. 
leda of tlie Hamilton, and which may be also compared wiJi Beus- 
hausen's Bellerophon macromyphalus F. Roemer, from the Spirifercn- 
sandstein was obtained at the Rio Maecuru. Among the Amazonian 
Devonian gasteropods, trilobed bellerophontids are strikingly abun- 
dant. There appear three distinct types of structure among them, 
namely one with a peripheral seam, and one without this seam, and 
a third type, embracing involute, laterally compressed shells having 
no seam. While Koken is disposed to regard Bucaniella as having 
possessed a seam, Clark restricts Bucaniella to the seamless, broad- 
backed Trilobatus (Conrad) group and describes two species as fall- 
ing under this genus, viz., B. reissi (M) and B. coutinhoana H. et R. 
(E), the former of which resembles closely Roemer's Bellerophon 
globatus Sow., from the Sjiiriferen-sandstein of the Hartz. For the sec- 
ond group (the broad, trilobed species having a seam) the name Plec- 
tonotus is introduced, and two species (Pl.derbyi and PL ? salteri, botli 
from Rio Maecuru) referred to it. The third group, which has been 
described by de Koninck under the name Tropidocyclus, is represent- 
ed by one species. T. gilletianus H. et R. from Erere. The latter is 
somewhat similar in specific details to the B. brevilineatus of the 
Hamilton shales. For a peculiar bellerophont from the Rio Maecuru 
which is constructed on the type of the B. patulus of the Corniferous 
and Hamilton faunas, a new genus, Ptomatis, is proposed on the 
ground of its deviation from the bellerophont-type. The species is 
named P. forbesi. A peculiar Tentaculites (T. stubeli) with more or 
less oblique annulations which are separated by somewhat inequal in- 
tervals, thus suggesting certain annelid tubes, is quite abundant at the 
Rio Maecuru. Another species (T. oseryi) has been collected in the 
Rio Curua sandstones, and a third (T. eldredgianus H. et R.) at Erere. 
The Pelecypoda are richly represented in the fauna of Maecuru. 
The essentially Devonian genus Actinopteria appears in two species, A. 
cschwegii, a form closely allied to the common Hamilton shale species. 
A. boydi, and A. humboldti. Another pterinaroid genus, Liopteria. 
has also been met with in two species, viz. L. browni and L. sawkinsi. 
The Modiolopsidse are likewise well represented by the genera Modi- 
omorpha and Goniophora; Modiomorpha with three species: M. hel- 
menreichi (M), a form pointing by the remarkable flatness of its 
valves to an earlier Devonian fauna; M. sellowi (M), which exhibits 
strong specific relations to M. complanata from the Corniferous lime- 
stone; and M. pimentana H. et R. (E). The only representative of 
the genus Goniophora is G. woodwardi (E). The TrigoniidcC of the 
Rio Maecuru district present some interesting features. Two forms, 
closely allied to Schizodus transversus Beush, differ like this in several 
important characters, notably the structure of the hinge, sufficiently 
