December 30, 1921] 



SCIENCE 



667 



This fauna belongs to the upper portion of the 

 Lower Cambrian, and it is essentially the same as 

 that found above the tunnel at Mt. Stephen, B. C, 

 and also found more or less all along the Cordil- 

 leran system down into southern Nevada. 



The stratigraphy of the section is as fol- 

 lows: 



Choeolate-brown shales 

 Lower — olenellus fauna. . . 50 + feet 

 Cambrian J fine-grained quartz con- 

 glomerate 300 + feet 



coarse conglomerate. . . 6 feet 



disconformity 

 purple and green mud 

 cracked siliceous me- 

 Precambrian targUlites (Siyeh) . . 300 ± feet 



Beltian Purcell lava — amygda- 



loidal basalt 100 feet 



purple and green mud 

 cracked siliceous me- 

 targillite and silice- 

 ous limestones 1,000 + feet 



(Siyeh formation) 



In the Cranbrook area the characteristics 

 of the disconformity between the Cambrian 

 and Precambrian are: 



1. The thickness of the sediments between 

 the Purcell lava and the basal conglomerate 

 of the Lower Cambrian varies from a few 

 feet to three hundred feet, showing evidence 

 of an unconformity. 



2. The upper surface of the Precambrian 

 does not show any evidence of weathering 

 before the deposition of the Lower Cambrian. 



3. The Precambrian and Cambrian strata 

 correspond in dip and strike. At no place 

 were discordant relationships observed. 



4. The metargillites of the Precambrian 

 are more highly metamorphosed than those 

 of the Cambrian. 



5. The contrast in lithology between the 

 Precambrian and Cambrian formations is 

 very marked. Mud cracked and ripple 

 marked purple and green metargillites are 

 characteristic of the Precambrian while the 

 Lower Cambrian rocks are white quartzose 

 conglomerates succeeded by grey and choco- 

 late-brown shales. 



6. The basal conglomerates of the Cam- 



brian contain rounded fragments of the under- 

 lying siliceous argillites. 



A full detailed statement concerning the 

 stratigraphical relationships of the Precam- 

 brian and the Cambrian over a wide area is 

 now in course of preparation to be published 

 by the Geological Survey of Canada. 



Stuart J. Schofield 



Univeesity of British Columbia, 

 Vancouver 



howardula benigna; a nema parasite 0» 

 the cucumber-beetle 



Bowardula ^ Cobb. Characters of Aphel- 

 enchus Bastian, 1865, but without oesophageal 

 bulb and with a non-bulbous onchium and 

 much reflexed ovary. " Female " finally a 

 flaccid, cylindroid sack, without distinct ali- 

 mentary canal, and otherwise much deterior- 

 ated. Syngonic; male unknown. Howardula 

 may be related to Bradynema zur Strassen, 

 1892, but the latter has no onchium and even 

 lacks a mouth opening. 



1.1 (?)5. 



(?)99, 



3.5-5. 



2.5 4.0 4.7 4.1 l.< 



Howardula henigna Cobb. Anus none or 

 vestigial; vulva sometimes terminal; uterus 

 nearly filling the body-cavity, posteriorly 

 packed with larvse and anteriorly with seg- 

 menting eggs, near the head in the vicin- 

 ity of the small spermathecum narrowed 

 and reflexed to the middle of the body, whence 

 the narrow ovary turns forward and ends 

 blind near the lead; onchium usually very 

 obscure but the minute mouth opening still 

 persisting. Inert, viviparous, usually all of 

 the same stage of development in any indi- 

 vidual host-insect, each when mature contain- 

 ing about two thousand embryos and segment- 

 ing eggs; the larvse, apparently always all of 

 one kind, sometimes ten to twenty thousand 

 of them, proceeding from the mother nemas 

 into the body-cavity, and into the sexual ap- 



1 Named for my distinguished friend Dr. L. O. 

 Howard, chief of the U. S. Bureau of Entomology, 

 president and past permanent secretary of the 

 American Association for the Advancement of 

 Science. 



