44 SAN DIEGO SOCIETY OF NATURAL HISTORY 
Illing (V. C.) Notes on certain Trilobites found in the Stockingford 
Shales. 
Brit. Assoc. Adv. Science, 83 Ann. Meeting, Sec. C, 1913. 
Abstract in Geol. Mag., Dec. V, vol. 10, p. 452, 1913. 
The author remarks that among the fossils found at Hartshill Hayes, numerous 
forms occur, representing young stages in the development of certain Trilobites. Among 
these are the following: . 
1. Liostracus sp., similar to one described by G. F. Matthew. 
2. Holocephalina sp. The early stages of this genus possess a well-marked glabella, 
widening anteriorly. 
3. Paradoxides Hicksii. 
4. Certain new forms of Agnostus. 
Jackel (O.) Ueber die Organisation der Trilobiten. 
Zeitschr. Deutsch Geol., Ges. 53, 1901, pp. 133-171, plates 4-6. 
Ueber verschhiedene Wege Phylogonetischer Entwickelune. 
Verhandl. des V. Internationalen Zoologen Congresses zu Berlin, 1901, pp. 1058- 
1117, 28 figures in text. 
Evolution of Trilobites, pp. 1086. 
The author illustrates Phacops, Agnostus and Olenus, fig. Nos, 20-24. 
On the evolution of Gigantostraca, p. 1105. 
liber die Aonostiden. 
Zeit. d. Deutsch Geol. Ges., vol. 61, 1909, pp. 380-401, figures 1-23. 
The author proposed Paragnostus with dgnostus rex as its type. This was the type 
of Corda’s Condylopyge. He further proposed Dichagnostus with 4 gnostus granulatus 
as the type duplicating Corda’s Pleuroctenium. The author gives the name of Mesag- 
nostus for 4. integer Beyr., which was used for Corda’s genus Peronopsis. 
Miagnostus Jackel has the same type species, 4. /aevigatus Dalm., as Lejopyge Corda. 
The new genus Leiagnostus, which has the same generic characters as Phalocroma 
Corda. 
Metagnostus erraticus and A. glabratus have the same short glabella with faint 
basal lobes as 4 gnostus tardus Barr., which was the type of Corda’s Arthrorhachis. 
Vogdes, in Am. Geol., vol. 9, 1892, p. 395, in his paper on North American species 
of the genus Agnostus, uses this term for section IV. 
The author arranges the families as follows: 
1. Fam. Paragnostidae. Paragnostus n. gen., type 4. rex Barr. 
Dichagnostus n. gen., type 4. granulatus Barr. 
Diplagnostus, type 4. planicauda Ang. 
Mesagnostus n. gen., type 4. in/eger Barr. 
2. Fam. Metagnostidae. 
Metagnostus n. gen., type M, erraticus n. sp. 
Hypagnotus n. gen., type 4. parvifrons Linnrs. 
3. Fam. Agnostidae sensu stricto. 
Agnostus sensu stricto, type 4. pisiformis Linné. 
Pseudagnotus n. gen., type 4. cyclopyge Tullberg. 
4. Fam. Leiagnostidae. 
Ptychagnostus n. gen., type 4. reticulatus Ang. 
Miagnostus n. gen., type 4. laevigatus Dalman. 
Leiagnostus n. gen., type L. erraticus n. sp. 
