. The elasmobranch fishes . Fig. 106. Muscles to the nictitating mem- brane and associated parts, lateral view, Mustelus californicus. , constrictor spiraculae; dl., dilator spiraculae; dp., depressor of upper lid; I., upper eyelid; n., nictitating membrane ; ?i^.,nictitator muscle; , superficial fibers which do not reach upper lid; sp., spiracle. VENTEAL CONSTRICTOES In Acanthias, according to Marion (1905) there may be two parts to the first ventral constrictor, the more anterior of which is the smaller and bridges the anterior symphysis of the lower jaw. The more posterior part is m
. The elasmobranch fishes . Fig. 106. Muscles to the nictitating mem- brane and associated parts, lateral view, Mustelus californicus. , constrictor spiraculae; dl., dilator spiraculae; dp., depressor of upper lid; I., upper eyelid; n., nictitating membrane ; ?i^.,nictitator muscle; , superficial fibers which do not reach upper lid; sp., spiracle. VENTEAL CONSTRICTOES In Acanthias, according to Marion (1905) there may be two parts to the first ventral constrictor, the more anterior of which is the smaller and bridges the anterior symphysis of the lower jaw. The more posterior part is much wider and is like that in Heptanchus. These parts take origin from a midventral seam and are inserted on the posterior margin of the mandible. In the rays the second part acts as a depressor mandibulae {, fig. 107b). The second ventral constrictor in the sharks is similar to that in Heptanch lis. This also arises from the midventral seam and is inserted on the border of the hyoid cartilage. In the rays the second ventral constrictor is divided into an anterior and a posterior part. The anterior part acts as a depressor hyomandib- idaris {, fig. 107b) , a muscle antagonistic to the levator hyomandibularis previously mentioned as derived from the second dorsal constrictor. The more posterior and narrower ventral part is the second ventral constrictor. Each of the remaining ventral constrictors in the rays () consists of two parts, a large outer and a small inner portion.
Size: 2524px × 1981px
Photo credit: © The Bookworm Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublisherberkeleycalifuniversityofcaliforn
