CAMBRIAN TRILOBITES WALCOTT 1 5 



Pygidium small, elongate, without defined segments. 



Genotype. — Burlingia hcctori, new species. 



(Observations. — This genus is represented by a single species from 

 the central portion of the Middle Cambrian fauna. The only form 

 with which it can be directly compared is Schiiialeiisceia ^loberg,^ 

 which is represented by specimens of the cranidium, pygidium. and 

 fragments of the thoracic segments belonging to a single species. 

 The cranidium of Schuialenseeia differs in having a convex glabella 

 divided into four lobes by four transverse furrows, and in the 

 presence of a defined occipital segment. The fragments of the 

 thorax illustrated by Dr. Moberg (1903, pi. iv) and his description of 

 them indicate that the pleurae were flattened and marked by shallow, 

 direct furrows similar to those on the pleurae of Burlingia. With the 

 present information, it is in the pygidium that the great difference in 

 the two genera is found. The pygidium of Schuialenseeia is large 

 and it has a strong axial lobe divided into a number of segments ; the 

 pleural lobes are broad and marked by numerous backward-curving, 

 fiat furrows much like those of the thoracic segments of Burlingia. 

 The pygidium of Burlingia is small and apparently without segments 

 or pleural lobes; it is a simple plate as in Parad oxides. 



Dr. Moberg ( 1903, p. 100) has noted the resemblance between the 

 direction of the facial sutures of Schuialenseeia and those of some 

 genera of the Cheirurid^e and Encrinuridse, while the broad anterior 

 margin of the head suggests some of the Conocoryphidas ; he con- 

 cludes that these resemblances have little value, as the other parts of 

 the shield differ so largely from the representatives of these genera. 

 In this I agree with him. The two genera are unlike all other trilo- 

 bites and form a family type by themselves. 



The genus is named after Mr. Lancaster D. Burling, of the United 

 States National ^luseum. who found the only three nearly entire 

 specimens of this interesting trilobite. 



BURLINGIA HECTORI, new species 



Plate i, Fiai-RE 8 



Dorsal shield small; longitudinally broad oval; slightlv convex. 

 Cephalon one-fourth the length of the complete dorsal shield, semi- 

 circular in outline, with genal angles prolonged into short slender 

 spines that scarcel\- extend beyond the extremity of the first or ante- 

 rior thoracic segment ; the posterior margin of the cephalon is nearly 



' Moberg. 1903, Meddelande fran Lunds Geol. Mineral. Inst. No. 5 ( Geol. 

 Koren. i Stockiiolm Forhandlingar, Bd. xxv. Haft 2. 1903, No. 2ig), pp. 93-102, 

 pi. IV. 



