REPORT OF THE DIRECTOR I918 I35 



II 



CRUSTACEA FROM THE PERMIAN OF SAO PAULO, BRAZIL 



Through the courtesy of Mr J. Pacheco of the Geographical and 

 Geological Commission of Sao Paulo, I have received a series of new- 

 crustaceans from the locality of Guarehy in the state of Sao Paulo, 

 the rocks of which are determined as of Permian age. I am not 

 aware of the collateral stratigraphic evidence upon which this deter- 

 mination has been based but all the evidence shown by the rock 

 specimens sent and independently of the crustacean remains, would 

 seem to corroborate this determination of their age. These speci- 

 mens are thin slabs of dark, chocolate-colored magnesian limestone 

 carrying considerable chert scattered through them in nodules and 

 mats, together with some noticeable quantity of pyrite. On the 

 surfaces of these slabs carapaces and other crustacean parts have 

 been flattened out and some of the fragments of rock are composed 

 of such debris. I have been asked by Mr Pacheco to identify and 

 describe these fossils. 



I find on solution of the matrix that the rock occasionally contains 

 traces of other organic remains replaced in silica, and among these 

 are parts of a Bellerophon and a Loxonema of types which might 

 fairly be regarded as appropriate to the Permian horizon. A single 

 specimen of the crustacean, replaced with chert, has given the true or 

 approximate contour of the carapace, and this has helped very 

 materially to illuminate the original form and probable relationship 

 of the species. In addition to this predominating and abundant 

 material are other remains occurring in a drill core of soft gray shale 

 taken from the same locality ; the latter crustaceans are of a different 

 character than the others. 



Paulocaris pachecoi sp. n. 



These carapaces vary in size from 15 to 20 mm in axial length and 

 in their flattened form have a semicircular or ungulate shape, notched 

 both back and front. At the front the axial line is extended into a 

 sharply angular and erect rostrum from the base of which an incurved 

 line passes on each side and terminates in a spinule, so that the front 

 margin bears a center spine or rostrum and two lateral spines or 

 spinules. The rear margin of the shield is more broadly incurved 

 in outline and thickened by an arched segment. In the axial line 

 and just back of the central point of the shield is a short, sharp and 



