138 NEW YORK STATE MUSEUM 



genera, cited below, from the figures and descriptions of a limited 

 number of authors whose works are conveniently at hand, and our 

 own observations. There is no doubt that the number of genera 

 and species in which the tubercle could be found is considerably 

 greater, but the list suffices to show the wide distribution of the 

 tubercle, on the glabella. A perusal of Schmidt's excellent photo- 

 graphs in his " Revision der baltischen Trilobiten," especially his 

 Lieferungen II and III, will give a clear conception of the regular 

 occurrence of the tubercle in the Asaphidae. The numbers behind 

 the authors refer to the bibliography in this paper. Figures where 

 the tubercles are shown are cited behind the species names. 



List of species with median eye tubercles 



Acidaspis ? : grayae, Reed, no. 22, pi. 16, fig. 2. 



Aeglina: princeps, Barrande, no. 1, pi. 14, fig. 3; prisca, ibid, 

 pi. 5, figs. 1, 2, 4, s ; pi. 8, fig. 5 ; pi. 14, fig. 1 ; r e d i v i v a , ibid, pi. 14, 

 figs. 10, 11 ; sulcata, ibid, pi. 8, fig. 1; um'bonata, Moberg, no. 1 1, 

 pi. 3, figs, ia, 3a. 



Agnostus: integer, Barrande, no. 1, pi. 49, fig. 1; granulatus, 

 ibid, pi. 49, figs. 5, 6; rex, ibid, pi. 49, figs. 4, 5; similar is, ibid, 

 pi. 14, fig. 18; perrugatus, ibid, pi. 14, fig. 16. A. girvanensis 

 Reed, no. 22, pi. 1, figs. 2, 4; sidenbladhi, Moberg and Segerberg, 

 no. 10, pi. 4, figs. 4, 5. Beecher, in diagram of Agnostus, Zittel-Eastman 

 Text-book, p. 624, fig. 1281A. Metagn ostus erratic us Jaekel, 

 no. 8, p. 382, fig. 1. Paragnostus rex, ibid, p. 397, fig. 12. D i - 

 • plagnostus planicauda, ibid, p. 3997, fig. 14, Miagnostus 

 laevigatus, ibid, p. 401, fig. 21. 



Ampyx: hornei, Reed, no. 22, pi. 3, figs. 8, 9 (see text fig. 44); 

 o b t u s u s , Moberg and Segerberg, no. 10, pi. 7, figs. 8, 9. 



Asaphus: (See Schmidt, no. 27, Lief. 2, p. 6, where the tubercle is figured 

 in all species represented, viz., A.expansus, raniceps, cor- 

 nutus, broggeri, eichwaldi, delphinus, laeviss- 

 i m u s var., laticauda, platyurus, latus, devexus, also A . 

 pachyophthalmus, ibid, p. yj, fig. 22; ibid, var. major, p. 40; 

 fig. 26; latus, p. 62, fig. 36; latus var. plautini, p. 64, fig. 37; 

 o r n a t u s , p. 69, fig. 38; 1 a e v i s s i m u s , pi. 5, figs. 1, 4, 5, 8; 

 ornatus, pi. 6, figs. 8, 8a ; devexus, pi. 7, figs. 1, 2; ludi- 

 b u n d u s , pi. 8, figs. 3 (also crest), 15a, 16 (pit). Barrande shows the 

 tubercle in diagrams of A . e x p a n s u s , pi. 2A, fig. 17, tyrannus, 

 ibid, fig. 23, also Salter, no. 23, pi. 22, fig. 5, also A . n o b i 1 i s , Schmidt, 

 pi. 31, fig. 1 (concentric rugae), pi. S7> hg- 4- Asaphus sp., Reed, no. 

 22, pt II, pi. 7, fig. 9. Schmidt (no. 27, Lief. 2, p. 8) states that the 

 tubercle is found in all species of Asaphus. 



Asaphellus: monticola Raymond, no. 17, pi. 14, fig. 4. 



Barrandiarcrassa, Barrande, no. 1, pi. 1 1, fig. 5. 



