266 Variation in the Mealworm, Tenebrio molitor 



No. 14. That the prothorax may be built up of two symmetlrical 

 disconnected halves (Fig. 4, p. 232) has been mentioned above already. 



No, 15. In consequence of a segmental anomaly in the larva, it was 

 also once remarked that the left half of the prothorax was imperfectly 

 developed with the whole leg, including the coxa, lacking. 



This absence of the leg was already noticed in the larva (Fig. 11 g). 

 Also the deviations No. 11 and No. 14 were found in beetles that were 

 distinguished by anomalies of the segments in the larval state. I shall 

 pass over the numerous asymmetrical deformities of the anterior, 

 posterior and lateral edges that bear the aspect of accidental disturb- 

 ances in the development. 



d. The Transverse Rib. 



Directly rostral to the distal prothoracic edge and bordering it, in 

 T. obscurus is found an elevation (Querwulst, bourrelet transversal) which 

 I will name the transverse rib. 



No. 16. This transverse rib is rarely, in T. molitor, found in such a 

 prominent form as is indicated in Fig. lie?. Between this development 

 and its complete absence a gradual series of more abundant transitional 

 forms may be met with. 



e. Grooves and Dints. 



Besides the usual fine punctulation, the dorsal surface of the prothorax 

 is rarely smooth. Generally there are found grooves, crater-like pits 

 (Fig. lie) or dints of various forms and extent. As a rule these pits 

 or dints are paired and lie symmetrically to the median line ; seldom are 

 they unpaired, as a single dint in the right or left half, but they never 

 occur in the median line. 



No. 17. A very curious form of cavity is pictured in Fig. 11 e^, 

 where a deep transverse groove right and left continues into another 

 groove which, running anteriorly and sideways, ends in a broadened dint. 



f. Scutellum. 



The variations in the scutellum are few in number and not con- 

 spicuous. Such a perfect semi-circular scutellum as T. picipes possesses 

 I have never observed in T. molitor, though cases were noticed approach- 

 ing it very nearly. 



No. 18. Only twice could the absence of the scutellum be established^ 

 once in the same beetle that produced the prothoracic anomaly mentioned 

 in No. 15. 



