224 Mr. F. Muir's Notes on the Ontogeny and Morphology 



grows out or evaginates, and eventually forms the eurazygos, 

 the stenazygos being formed by an invagination at the 

 apex of the eurazygos. The first differentiation of the 

 eurazygos is a constriction near the base, differentiating 

 the tegmen from the median lobe.- This I call the tegminal 

 fold, and it is of great morphological importance ; from it 

 are developed the tegminal lobes as two evaginations, and 

 the tegminal strut as a single invagination. In R. obscura 

 (Boisd.) there are no tegminal lobes, but there is a large 

 strut, the origin of which as an invagination eventually 

 becoming thickly chitinised is quite plain. The portion of 

 the eurazygos distad of the tegminal fold develops into 

 the median lobe and the internal sac ; at first there is no 

 differentiation between these two, but at a later stage the 

 basal portion becomes chitinised and differentiated as the 

 median lobe, while the distal portion remains membranous 

 and as it increases in size it crumples up and ultimately 

 it is withdrawn into the median lobe, but not until the 

 beetle is fully developed and has left the pupal skin. In 

 R. obscura (Boisd.) there is a pseudo-tegmen formed by the 

 chitinisation of the connecting membrane between the 

 tegmen and the wall of the abdomen, and in this species 

 the spiculum gastrale arises as an invagination from the 

 pseudo-tegmen. 



The male genitalia of Coccinella repanda arise in a similar 

 manner from the same position between the ninth and tenth 

 sternites. Soon after the tegminal fold is developed two 

 broad, flat processes grow out from it, and a small invagina- 

 tion takes place on the opposite aspect of the fold ; the 

 former are the tegminal lobes and the latter is the tegminal 

 strut. The tegminal fold beneath (or at the base of) the 

 tegminal lobes grows outward carrying the tegminal lobes 

 with it, and eventually forms the median " cap-piece." 

 The median lobe elongates and muscles connect its base 

 with the tegminal strut, and as it lengthens and grows 

 inward it becomes curved. The spiculum is formed by an 

 invagination near the base of the ninth sternite. 



Carpophilus humeralis also follows a similar line of 

 development, the tegminal lobes first appearing as broad, 

 rounded outgrowths of the tegminal fold, the tegminal 

 strut being very small. The apical portion of the eurazygos 

 is invaginated at an early stage and grows inward to a great 

 length, an examination takes place at the junction of the 

 eurazygos and stenazygos which lengthens into the tine, 



