. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 320 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY Metathorax. The xiphus (" sternelliim" of Griffith, 1945) of the metasternuni is considerably larger than those of the preced- ing two segments (Fig. 13, XIII). Along its posteroventral margin runs a ridge (SS) which resembles the xiphal ridges of the prothorax and mesothorax. Since it ends at the bases of the metathoracic furcae, however, it may represent a sternacostal suture. If so, the part of the sternum anterior to it may be termed the hasisternum, and the s
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 320 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY Metathorax. The xiphus (" sternelliim" of Griffith, 1945) of the metasternuni is considerably larger than those of the preced- ing two segments (Fig. 13, XIII). Along its posteroventral margin runs a ridge (SS) which resembles the xiphal ridges of the prothorax and mesothorax. Since it ends at the bases of the metathoracic furcae, however, it may represent a sternacostal suture. If so, the part of the sternum anterior to it may be termed the hasisternum, and the short portion posterior and lateral to it (the posterodorsal wall of the xiphus) may be pRm-i r-Esnr EPm- i ' r-wpm CPULâ7^- ⢠^'' â ^-POBE -EPE poBm- Z^''''''*^ ^'"^''issss^V'"^^ wpi PEn- TNHI. S2 T64 ' ^ â «"«' '" ' ^-^ ^ "^^ PAE FA /^^-^ -\âCPU T42 TNH T40 FIE"- -K^^y^^ VTP>%:"-'-|âPE^ ,-/: L-FE #-⢠\ ^^^-\^at^ / /.«»«-^-. -/---T40 m SR RG T4I XG Figure 15. Dorsal view of the inuer surface of the pterothorax, left side, allowing the sterna and pleura. The pterotergum has been cut off at the postalar bridges and at the mcsothoracic prealar bridge, and the tendons in the pericoxal membranes have been cut off near tlieir bases. The muscles have been removed. called the siernellum or furcasternuin. Extending between the metathoracic furcae is a membrane which separates the meta- thoracic sternum from the sternum of the first abdominal segment. The f ureal pits are concealed externally by the lateral edges of the xiphus. Internally the furcae appear as two unbranched processes (Figs. 12 and 15, Fill). They extend posterolaterally and are longer and much more slender than the mesothoraeic Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harv
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