. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 112 ANNALS OF THE SOUTH AFRICAN MUSEUM phusa guerini (Patwardhan, 1935), may be divided into two main categories. The extrinsic muscles are those which originate outside the fore-gut, generally on different parts of the exoskeleton; most of them are inserted on the ossicles of the fore-gut and serve to dilate its parts. On the other hand, the intrinsic muscles function as constrictors and usually have their attachments and inser- tions on the proventricular ossicles; it has been shown by Manton (1928
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 112 ANNALS OF THE SOUTH AFRICAN MUSEUM phusa guerini (Patwardhan, 1935), may be divided into two main categories. The extrinsic muscles are those which originate outside the fore-gut, generally on different parts of the exoskeleton; most of them are inserted on the ossicles of the fore-gut and serve to dilate its parts. On the other hand, the intrinsic muscles function as constrictors and usually have their attachments and inser- tions on the proventricular ossicles; it has been shown by Manton (1928, 1934) that many of the intrinsic muscles are derived from the preantennulary meso- derm. The arrangement of the muscles in J. lalandii closely resembles that of Cancer and Paratelphusa, and the terminology used in the following account is in accordance with that of Pearson (1908). lateral cord io-pyloric median cordio-pyloric anterior gastric upper ant. dilator of fore-gut—jj antero - latero I cardiac anterior cardiac antero-iateral dilators of fore-gut lower anterior dilators of fore-gut i,nner posterior gastric outer posterior gastrics. ant. & post, dorsal pyloric dilators postero - inferior cordiac ventral pyloric dilator . , , .-, . '*<5fciix::::/^^^ ^posterior dilator of fore-gut upper anterior oesophageal dilator-. '€^^/A—ii„m\ ^^?^^llllm \postero-lateral di lator of fore-gut lateral oesophageal dilate lower anterior oesophageal dilator [T^^^posterior oesophageal dilator oesophageal constrictors Fig. 35. Left lateral view of fore-gut, showing position of muscles; intrinsic muscles are underlined. (a) Extrinsic muscles Anterior gastrics: one pair of broad muscles attached to the procephalic processes. Each passes somewhat obliquely backward and is inserted on the posterior half of the cardiac ossicle. As some of the fibres are inserted on the median ridge of the cardiac ossicle, there is only a slight gap between the posterior ends of the two muscles. Post
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