Feb., 1912. Mammals or Illinois and Wisconsin — Cory. 491 



Pentadactylous — With five fingers or toes. 



Placenta — The organ by which the fetus of the higher mammals is nourished. 



It is connected with the fetus on one side by the umbilical cord and on the 



other is attached to the walls of the uterus, from which it is detached at birth. 

 Plantar tubercles — Wart-like excrescences on under surface of foot. 

 Plantigrade — Walking on practically the whole sole of the foot. 

 PoUex — The thumb or first toe of front foot. 

 Postorbital — Behind the eye. 



Premolars — Teeth in side of jaw between the molars and the canine. 

 Ramus, pi. rami — ■ The ascending part of the lower jaw at the posterior end. 

 Rostrum — The part of the skull in front of the eyes, made up of the nasal and part 



of the premaxillary and maxillary bones; practically, the snout. 

 Sagittal crest — A bony ridge along the middle upper surface of the brain case in 



some mammals. 

 Sectorial — Adapted for cutting; usually used to describe certain teeth. 

 Septum — A partition. 

 Skin — Consists of two layers: an outer one termed the epidermis or cuticle (which 



has no blood vessels), beneath which is a second layer or true skin, variously 



called dermis, corium or cutis i;era, which is abundantly supplied with nerves and 



blood-vessels. The skin covers the outer surface of the body and continues in a 



softer and somewhat modified form (termed mucous membrane) as a lining for 



the internal passages, such as the digestive and urogenital tracts. 

 Squamate — Scaly or covered with scales. 

 Squamosal bone — See chart, p. 11. Forms part of the temporal bone in man; 



what answers to the squamous portion in man is called the squamosal in lower 



animals. 

 Squamous — Covered with scales, scaly or resembling a scale. 

 Sulcate — Grooved. 



Supraorbital — Expansion of bone above the eye, noticeable in the Hares and Rabbits. 

 Suture — Line of union or point of junction of two bones, which ultimately unite 



and become immovable. 

 Synonym — One of two or more names for one and the same thing. 

 Tactile — - Pertaining to the sense of touch. 

 Tail vertebrse or caudal vertebrae — See page 10. 

 Tarsus — Bones forming the ankle joint. See chart, p. 10. 

 Tautonym — Binomial name, having generic and specific names alike. 

 Terrestrial — Living on the ground. 



Thoracic — Used here as pertaining to the chest or thorax. 

 True skin — Inner portion of the skin known as dermis or corium or cutis vera. 

 Tooth row — Continuous row of teeth on side of jaw posterior to the canine (most 



commonly used in describing Rodents). 

 Topotype — A specimen collected in the exact locality where the original type was 



obtained. 

 Tragus, pi. tragi — An erect cartilaginous process in the conch or external ear of a 



bat. 

 Trochanter — One of the bony processes of the thigh bone. 

 Truncate — Blunt. 

 Tuberculate — Having tubercles or small projections; commonly used in this work 



in describing teeth. 

 Type [of genus] — The species which was originally designated or later selected 



in conformity with the rules of zoological nomenclature to typify a genus. 



