STUDIES ON THE A1?ACHNID ENTOSTEHN ITK. 237 



complete ami distinct apophyses. This cleavage appears to 

 have taken place, probably once, possibly twice, in the case 

 of the entosternite of Phrynus. 



In none of the Arachuoniorphse have I found ventral 

 apophyses extending to the sternum, such as are found in 

 all the Mygalotnorpha3. The underside of tiie entosternite 

 of Lycosa ingeus, however, is furnished in its anterior 

 half with a high median crest, from which five short and 

 slender tendons arise on each side. These tendons appear 

 to be homologous with the five inferior tendons seen in 

 Ephebopus (fig. 13) and other genera of Aviculariidae. In 

 the latter, however, only three pairs spring from a common 

 centre, the first lying far forward; the fifth, often obsolete, 

 far backwards. 



The diagrammatic transverse section of the entosternite, 

 with its associated muscles, of the Ai-aneee, figured by 

 >Schimkewitsch (10), shows on each side two dorso-ventral 

 muscles, a lateral muscle, and two that pass to the legs, an 

 external or elevator of the trochanter (second segment), and 

 an internal (the depressor of the coxa), which passes ventraliy 

 to an eutapophysis between the sternum and the base of the 

 leg, — all rising from distinct apophyses. The last-named 

 muscle is, 1 believe, the vential portion of the tergo-sternal 

 muscle, and the pair of dorsal muscles on each side repre- 

 sent the tergal portion cleft to the base. 



5. The "So-called" Entosternite of the Solifugr 



as. 



The "so-called" entosternite of the Solifugae, both in its 

 structure and attachment, is quite unlike the true entoster- 

 nite of other Arachnids. It consists of a pair of stout, rigid 

 chitinous pillars united, with or without articulation, to the 

 narrow prosternal plate, wedged in between the coxio of the 

 third pair of appendages. From the presternum it extends 

 transversely along the narrow strip of integument joining the 

 juxtaposed coxae of the third and fourth pairs of appendages. 

 Internally the two pillars, running oblicjuely oi" subvertically 



