NO. 3 CAMBRIAN TRILOBITES 221 



Geographic distribution. — Vanuxemella contracta occurs (locali- 

 ties 4V, 5J) in the Lewis and Clark Forest Reserve of northern 

 Montana, and Vanuxemella nortia at about the same stratigraphic 

 horizon, judging from the associated fauna, on the south slope of 

 Mount Bosworth (locality 35c), British Columbia, Canada. 



Observations. — This genus is represented by two species from the 

 upper part of the Lower Cambrian. It is a simple form that has 

 some features suggesting Albert ella.^ It differs in absence of glabel- 

 lar furrows, shorter eye lobes, absence of prolonged third segment 

 of thorax, and in having four instead of seven thoracic segments. 

 The long spines of the pygidium spring from about the fifth segment, 

 while in Albertella they appear to be the extension of the first or 

 second anterior segment. 



Vanuxemella also has an interesting feature in the union in the 

 pygidium of three otherwise true thoracic segments. If these three 

 anterior segments were free, the resemblance to Albertella would be 

 much stronger. The genus may be characterized as an undeveloped 

 form of the latter genus. 



The cephalon of Karlia stephenensis Walcott'' has an expanding 

 glabella, but it also has quite a different glabella and fixed cheeks, 

 and it has seven segments and a minute pygidium. 



The generic name is given in memory of Lardner Vanuxem, the 

 geologist who surveyed the " Third District of the State of New 

 York." 



VANUXEMELLA CONTRACTA, new species 



Plate 36, figs. 4, 4a 



The description and observations under the genus and the illus- 

 trations give all that is known of the species. There are five entire 

 specimens and a few cranidia. 



Dimensions. — A dorsal shield 12 mm. in length has the following 

 dimensions : 



Cephalon. mm. 



Length 6 



Width at posterior margin 9 



Width of base of glabella 8 



'' Smithsonian Misc. Coll., Vol. 53, 1908, pis. i and 2. 



'Proc. U. S. Nat. Mus., 1888, Vol. 11, 1889, p. 445- See plate 2,6, fig. 8, of 

 this paper. 



