180 CALIFORNIA ACADEMY OF SCIENCES. 



In this contribution the initials of each author designate the paragraphs 

 written by him. 



The following list is given of the Trilobite fauna of the Skiddaw slates: 

 Phacops nicholsoni Salt. Cybele ovata Eth. Calymene brevicapitata ? 

 Bemopleurides SI) . 1 Olenus S'p.^. Trinucleus gibbsii ? Sa,lt. Ogygia selwyni 

 Salt. Ogygia sp.l Barrandia falcataV . &, G . Niobe doveri'Eth. Evrymeto- 

 pus n. g., E. cambrianus n. sp. P. & G., E. harrisonii P. & G. jEglina ? 

 rediviva^&rr., A. binodosa Salt., A. obtusicauda Hieks, A.? caliginosa Salt. 

 Agnostus morei Salt. 



Prestwich (S.) On the geology of Coalbrook Dale. 



In Trans. Geol. Soc. London, vol. 5, 1840, p. 413, map, 2 sections, 4 

 pis . 



The author mentions Asaphus caudatus Briinn, A. tuber culato-caudaius 

 Murch., A. longicaudatus Murch. Calymene blumenbachii Brong. 



On plate 41 he illusti-ates Limulus anthrax n. sp., L. rotundatus n. sp., 

 L. trilobitoides Buckland. Apus dubius n. sp. Anthrapalcemon (Palceo- 

 rarabus) dubhis Salt. 



Dr. Woodward uses Limulus anthrax and L. rotundata for the types of 

 his new genus Prestioichia. 



After a careful study of the Limuli belonging to Prestwich's collection, 

 and also other specimens, this author remarks, that ■they are divisible into 

 two well-marked genera: 



(a) Those having movable thoracic segments and aucbylosed abdomina 

 ones; to be included in the genus Belinurus, namely Belinurus trilobitoidesl 

 Buckland, etc. 



(b) Those in which the thoracic and abdominal segments are not divided, 

 and which the former appear to be anchylosed. Prestwichia anthrax and 

 P. rotundata. 



Quenstedt (F. A.) Beitrage zur Kenntniss der Tril- 

 obiten, mit besonderer. Riicksicht auf ihre bestimmte 

 Gliederzahl, 



In Archiv fur Naturgesch. (Wiegmann), vol. 1, Berlin, 1837, p. 337. 

 This work divides the Trilobites into two groups: 



1. Trilobites with faceted eyes. 



2. Trilobites with non-faceted eyes.' 



The genera are classified according to the number of segments in the 

 thorax, as follows: 



With 13 segments in the thorax: Trilobites blumenbachii Brong. (Caly- 

 mene callicephala Green, C. seUnocephala Green ?, C. platys Green. 



Trimerus delphinocephalus Green. Calymene polytoma Dalm., C. bella- 

 tula Dalm. Anaphus fischeri Eichw. These Trilobites form, perhaps, a 

 second section among the Trilobites with 13 segments. Their segments 

 are smooth and without grooves. 



