388 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



Perhaps the most interesting Triassic fern family, and next to the 

 Marattiaceae in importance at that time, was the Dipteriaceae. 

 Surviving in only four species with a limited range from India to 

 New Caledonia, they were represented during Triassic times by the 

 genera Protorhipis, Clathropteris, Dictyophyllum, Thaumatopteris, 

 Camptopteris (fig. 32), characterized by their dichotomous fronds. 



Fig. 32. — Restoration of Camptopteris (after Nathorst), X 1/4. 



indeterminate growth, and netted-veined pinnae suggestive of a leaf 

 of a chestnut oak. These ferns were practically cosmopolitan dur- 

 ing the late Triassic, especially in the two closely allied genera 

 Clathropteris (fig. 34) and Dictyophyllum (fig. 33). Protorhipis 

 did not attain its maximum range until later in the Mesozoic, while 

 Thaumatopteris and Camptopteris were always more restricted in 

 their range, 



