Proceedings of the Scientific Meetings of the Zoological Society of London 1876

Page 109

1876.] MR. E. R. ALSTON ON THE ORDER GLIRES. 75 panying chart (Plate IV.), on which I have endeavoured to indi­cate approximately the relationship of the different families to one another. Arrangement. Order G L I R E S . Suborder I. GLIRES SIMPLICI- Sec. 3. Hystricomorpha. DENTATI. Fam. 1. Octodontidae. Sec. 1. Sciuromorpha. „ 2. Hystricidae. Fam. 1. Anomaluridae. „ 3. Chinchillidae. „ 2. Sciuridae. ,, 4. Dasyproctidae. ,, 3. Ischyromyidae. „ 5. Dinomyidse. „ 4. Haplodontidae. „ 6. Caviidae. „ 5. Castoridae. Sec. 2. Myomorpha. Suborder II. GLIRES DUPLICI - Fam. 1. Myoxidae. DENTATI. ,, 2. Lophiomyidae. Fam. 1. Lagomyidae. „ 3. Muridae. „ 2. Leporidae. „ 4. Spalacidae. " 5. Geomyidae. Suborder III. GLIRES HEBETI- „ 6. Theridomyidae. DENTATI.. „ 7. Dipodidae. Fam. 1. Mesotheriidse. Table of Characters. Order GLIRES. The middle pair of incisors long, curved, rootless, and constantly growing, their points more or less chisel-edged (except in Mesothe­rium), the other pairs very small or absent; no canines, a large space intervening between the incisors and the grinding-teeth, which are variously formed ; premolars present or absent; three molars above and below (except in Hydromys). Skull with the temporal fossae continuous with the orbits, within which the lachrymal fora­men opens ; an interparietal almost always distinct; the periotic and tympanic ankylosed to one another, but not to any other bone ; and the auditory bullae moderately or largely developed. Scapula nar­row with a deep notch, a well-developed more or less bifurcated acromion, and a small coracoid. Clavicles perfect or imperfect. Scaphoid and lunar usually combined. Manus with five or four digits. Tibia and fibula either separate or ankylosed below. Pes with five, four, or three digits. Intestinal canal long; caecum large (except in Myoxidee). Liver with a bifid Spigelian lobe (except in Anomalurus). Placenta deciduate and discoidal. Suborder I. GLIRES SIMPLICIDENTATI. Incisors § only, even at birth, their enamel confined to the front surface. Skull with both a true alisphenoid and an external ali­sphenoid canal* ; optic foramina rarely confluent; incisive foramina separate • and bony palate well developed. Fibula either ankylosed * Cf. H. N. Turner, P. Z. S. 1848, p. 65.