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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



SUMMARY 



1. Each thoracic ganglion of Dissosteira Carolina gives off three 

 pairs of nerve roots. Nerves from the first of these roots inner- 

 vate the dorsal longitudinal muscles, hence the root and its main nerve 

 is designated as the dorsal nerve. Each dorsal nerve has an anterior 

 connection with the ganglion anterior to it. 



2. The nerves from the second root innervate muscles of the an- 

 terior part of the segment; nerves from the third root innervate 

 muscles of the posterior part of the segment and of the leg. In these 

 respects Dissosteira agrees closely with Chauliodes (Neuroptera) as 

 described by Maki (1936). 



3. The innervation pattern of the depressor of the trochanter sup- 

 ports the belief that this muscle group originated from two primitive 

 muscles. 



4. The cervical musculature is innervated by two fine nerves from 

 the suboesophageal ganglion and by the prothoracic dorsal nerve. 



5. The pterothoracic dorsal nerves pass beneath the ventral longi- 

 tudinal muscles, differing in this respect from the prothoracic and the 

 abdominal dorsal nerves of Dissosteira, and from all thoracic and 

 abdominal dorsal nerves of Chauliodes. 



6. The nerves to the thoracic spiracle muscles agree sufficiently 

 with the nerve pattern of the abdominal spiracles to indicate that the 

 thoracic spiracles may be homologous with the abdominal spiracles. 



ABBREVIATIONS USED ON THE FIGURES 



ACn, anterior ganglionic connective. 



AWN, anterior wing nerve. 



icv, 2CV, first and second lateral cervi- 

 cal sclerites. 



iCvN, first cervical nerve. 



2CvN, second cervical nerve. 



Cx, coxa. 



del, lateral external dorsal muscles. 



dcm, median external dorsal muscles. 



dil, lateral internal dorsal muscles. 



dim, median internal dorsal muscles. 



dlsp, dilator muscle of the spiracle. 



DN, dorsal nerve. 



Gngi, prothoracic ganglion. 



Gng2, mesothoracic ganglion. 



Gngs -{- lA -{- 2A ■\- 3 A, definitive 

 metathoracic ganglion. 



HNv, segmental heart nerve. 



is, intersternal muscle. 



it, intertergal muscle. 

 Ic, external lateral muscles. 

 //, internal lateral muscles. 

 MdN , median nerve. 

 OS, outer sternal muscle. 

 osp, occlusor muscle of the spiracle. 

 ot, outer tergal muscle. 

 p, paratergal muscle. 

 p-cv, postocciputal-cervical plate mus- 

 cle. 

 PIA, pleural apodeme. 

 Poc, postocciput. 

 PrmdN, paramedian nerve. 

 PT, posterior arm of the tentorium. 

 PWN, posterior wing nerve. 

 SA, sternal apophysis. 

 SlGnN, salivary gland nerve. 

 SoeGng, suboesophageal ganglion. 

 Spyi, spina. 



