586 CALIFORNIA ACADEMY OF SCIENCES. l8 



C. Base of skull nearly straight (slightly curved). Interorbital space flat 

 or slightly concave, of medium width, 4 to 4 J- in base of skull. Pro- 

 cesses of mesethmoid directed but little upward. Ventral process, of 

 basisphenoid rudimentary or poorly developed. Cranial ridges and 

 spines quite strong. 



j. Cranial ridges well developed. Preocular, supraocular, postocular, 

 tympanic, parietal and nuchal spines present. Coronal spines usu- 

 ally present, introniger, aurora. 



D. Base of skull straight or nearly so. Interorbital space concave and 

 narrow, 4£ to 6f in base of skull. Processes of mesethmoid directed 

 upward. Ventral process of basisphenoid well developed. Cranial 

 ridges high and strong. 



k. Supraocular spine present. Parietals not meeting. 



I. Skull thick; cranial ridges broken into tubercles and spines; in- 



terorbital space flat; mesethmoid processes horizontal; ventral 

 process of basisphenoid rudimentary in adult (the skull of young 

 almost exactly as in rosaceus; see below), ruberrimus. 



II. Skulls somewhat papery; ridges smooth; interorbital space con- 

 cave; mesethmoid processes directed upward; ventral process of 

 basisphenoid well developed in both young and old. conslellalus, 

 rosaceus, rhodochloris, chlorostictus. 



kk. Supraocular spine absent. 



m. Interorbital space not widening markedly backward, 

 n. Parietals not meeting; skull papery, elongatus. 

 nn. Parietals meeting; skull bony. 



o. Nuchal spines none, rubrivinctus, levis. 

 00. Nuchal spines present; ridges thick and high, serriceps. 

 mm. Interorbital space widening markedly backwards; parietals not 

 meeting, 

 p. Coronal spines present, skull bony, auriculatus. 

 pp. Coronal spines none. 



q. Skull thick; bones striated; interorbital space slightly con- 

 vex, rastrelliger. 

 qq. Interorbital space concave and the cranial ridges strong and 

 high, vexillaris, maliger, carnatus, chrysomelas, nebulosus. 



The interorbital space becoming more concave and narrower 

 and the ridges stronger and higher from the beginning to the 

 end of the series. 



It has been impracticable in some cases to separate 

 closely related species in the above classification accord- 

 ing to cranial characters, some of them agreeing even in 

 color patterns and differing only in colors and other de- 

 tails, and showing no tangible differences in the skulls. 



