706 CAMBRIAN BRACHIOPODA. 



(161) Limestones of the Paradoxides davidis zone at Borregaard ; (16i) limestones of the Conocoryphe exsulans zone 

 at Borregaard; (16j) limestones of the Paradoxides forchhammeri zone at Laesaa; (I6I1 and 3341i) limestones of the 

 Paradoxides forchhammeri zone at Boiregaard; and (16k) limestones of the Paradoxides davidis zone at Laesaa; all on 

 Bornholm Island, Denmark. 



Specimens somewhat doubtfully compared with Acrotreta sagittalis occur at the following 

 locality : 



Middle Cambrian: (317a [Davidson, 1871, p. 340]) at Bellewstown, County Meath; and at Balbriggan, County 

 Dublin; both in Ireland. 



Acrotreta cf. sagittalis. 



High up in the Middle Cambrian of the House Range, Utah, there is a small, depressed 

 species of Acrotreta that appears to be identical with A. sagittalis as the latter occurs in Sweden 

 and Newfoundland. Some of the ventral valves are very low, but specimens of a similar char- 

 acter occur in the limestones of Sweden and Newfoundland. 



Formation and locality. — Middle Cambrian: (lln) About 3,000 feet (914.4 m.) above the Lower Cambrian 

 and 1,400 feet (426.7 m.) below the Upper Cambrian, in the upper part of the limestone forming la of the Marjum 

 limestone [Walcott, 1908f, p. 179], in the long cliff southeast of Marjum Pass [Walcott, 1908f, Pis. XIII and XV], 

 House Range, Millard County, Utah. 



A somewhat similar shell that also strongly suggests Acrotreta sagittalis occurs in the 

 Middle Cambrian limestones near Antelope Springs, in the House Range, Millard County, 

 Utah. As the material is not very good or abundant, nothing more will be done at present 

 toward identifying it. 



Acrotreta sagittalis magna (Matthew). 



^ Plate LXVI, figures 4, 4a-f . 



Linnarssonia belli magna Matthew, 1897, Trans. Roy. Soc. Canada for 1897, 2d ser., vol. 3, sec. 4, No. 7, pp. 169-170, 

 PL I, figs. la-b. (Described and discussed as a new variety. The specimens represented by figs, la and lb 

 are redrawn in this monograph, PL LXVI, figs. 4b and 4-4a, respectively.) 



Acrotreta sagittalis magna (Matthew), Walcott, 1902, Proc. U. S. Nat. Mus., vol. 25, pp. 595-596. (Discussed as 

 below.) 



In addition to the material collected by Matthew, I have a number of specimens collected 

 by me at the typical locality at Hastings Cove. A comparison with a series of specimens of 

 Acrotreta sagittalis (Salter) from St. Davids, Wales, and of A. sagittalis transversa (Hartt) 

 shows at once that the form Matthew named is veiy closely related to both. The length and 

 size of the median ridge, and the position of the central scars of the dorsal valve, and the size 

 and position of the cardinal scars of the ventral valve are the internal characters that Matthew 

 depends upon to distinguish the variety magna. All of the characters are fully covered, by 

 the vaiiations in the same characters in A. sagittalis and its variety transversa. The nearly 

 circular form of the variety magna is about the only character that can be considered of value, and 

 that is very closely approached by some specimens of A. sagittalis (PI. LXXI, figs. 3b, 3e, 3h). 



It is not probable that the New Brunswick shell is a variety of Acrotreta helti (Davidson) 

 (PI. LXXVII). In order to have all the data possible for the student I have illustrated 

 Matthew's types, which he kindly sent me for tlie purpose, also specimens I found in the lime- 

 stone at the base of the beds carrying Paradoxides at Hanford Brook. 



Formation and locality. — Middle Cambrian: (2s) <^ Limestones in upper part of Paradoxides zone, Hastings 

 Cove [Matthew, 1898b, p. 38], on Kennebecasis Bay, 0.5 mile {0.8 km.) northeast of Torryburn, on the Intercolonial Rail- 

 way, northeast of St. John; (2i) sandstones of Division lb3 of Matthew's [1895a, p. 108] Protolenus zone, Hanford 

 Brook; and (21) limestones at base of Paradoxides zone, Hanford Brook; all in St. John County, New Brunswick, 



a 2s is the type locality, though the specimens in the United States National Museum collections to which that number is assigned were 

 collected later than the type specimens. 



