'10 Scientific Intellige 



nee. 



stalked eyes are regarded as representing the first pair. These 

 "are not very unlike those of recent crustaceans of the same 

 orders," while the thoracic appendages appear to be based on the 

 typical crustacean biramose limb. 



The author thinks it probable that the Branchiopoda, Mala- 

 costraca, Ostracoda, Trilobita, and Merostomata had their origin 

 previous to the Cambrian. In regard to Bernard's interesting 

 theory that Apus was developed out of a "browsing carnivorous 

 annelid with its first 5 segments (head) bent so that its mouth 

 faced ventrally and posteriorly," Walcott "examined the Bur- 

 gess shale annelidan and crustacean fauna to ascertain if there 

 was an annelid that could be considered as representing his hypo- 

 thetical crustacean annelid, and nearer to it in structure than 

 Apiis. I found specimens of Canadia spinosa Walcott laterally 

 flattened in the shale with the head bent down, so that the mouth 

 faces posteriorly (Smiths. Misc. Col., 57, No. 5, 1911, pi. 23, fig. 

 4), also that 14 out of 24 specimens have the head bent under 

 and out of sight beneath the flattened body. Possibly these 

 annelids and the crustaceans were derived from the same general 

 type of animal" (162). 



"As to the relations of the Branchiopoda, Leptostraca (repre- 

 senting the Malacostraca), Trilobita, and Merostomata the inter- 

 relationship of the four so-called subclasses is found to be very 

 intimate. In Opablnia and Leanchoilia the typical branchiopod 

 is clearly present. In Waptia the Leptostraca is very near at 

 hand as developed in Hymenocaris, 



"In Marrella the trilobite is foreshadowed, and JVathorstia is a 

 generalized trilobite as the trilobite appears to be a specialized 

 branchiopod, adapted largely for creeping on the bottom. The 

 trilobite gives some conception of a possible form between the 

 Branchiopoda and the Aglaspidse of the Merostomata" (163). 



From the ApodidaB "it is assumed that the Branchiopoda came, 

 and from the Branchiopoda stock three distinct branches were 

 developed prior to or during Cambrian time." In one line of 

 descent "it is assumed that the Trilobita are directly descendent 

 from the Branchiopoda and forms grouped under the order 

 Aglaspina derived from the Trilobita. The order Limulava is 

 considered as being intermediate between Aglaspina and the 

 Eurypterida, and that the two orders Limulava and Aglaspina 

 serve to connect the Trilobita and the Eurypterida. 



"From the Eurypterida we pass to the Xiphosura. It is 

 thought that the Phyllocarida, as represented by the group of 

 forms included under the Hymenocarina, came from the Branchio- 

 poda, but on a different line of descent from the Trilobita and 

 the orders grouped under the Merostomata. 



"The ostracods are assumed to have been derived from the 

 Branchiopoda, but on a different line of descent from the Trilo- 

 bita and Phyllocarida" (163-4). c. s. 



5. Strophome?ia and other fossils from Clncinnatian and 

 Mohawkian horizons, chiefly in Ohio, Indiana, and Kentucky ; 



