The various genera and species of the Orthopteran sub-family Tet- tigidae may be recognized under several names in the reports of a number of entomologists. They range from the form Bulla of LINNE (1767), whose figures are unmistakable, to the recent descriptions of SCUDDER (1900), HANCOCK (1902), and other orthoptologists. Such words as Tettix, Tettiginae and Tettigidae apparently were derived from "tettix" of Greek origin, meaning grasshopper. The common name, "Grouse locust", has probably been applied because of a fanci- ful resemblance of some of these insects to the grouse (Tetraoninae). B I 0 LOG Y 0 F THE GR 0 USE L 0 C U S T S The Distinguishing Characteristics. The following discussion con- cerning the characteristics which distinguish the Grouse Locusts is largely from the detailed descriptions by HANCOCK (1902) and Ro- BERTSON (1915). (See Fig. I). FIG. 1. Lateral, dorsal and frontal aspects of the body of a typical grouse locust, Acrydium (From HANCOCK) They are among the smallest of the Orthoptera. The extremely de- veloped apical process of the pronotum extends backward over the 30 THE GENETICS OF THE TETTIGIDAE (GROUSE LOCUSTS) Explanation of Plate I (All figures from HANCOCK, 1902) FIG. 1. Choriphyllum /oliatum HANCOCK. Female from Jamaica. FIG. 2. Nymph of Acrydium obscurus HANCOCK. FIG. 3. Tettigidea parvipennis preparing the burrow for the eggs. FIG. 4. Acrydium granulatus SCUDDER. Female. FIG. 5 and 6. Dorsal and profile views of posterior abdominal appen- dages of a male Acrydium hancocki MORSE.