. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 121 apparently no uniform structural plan, and some of the most interesting variations elucidated by Marchal relate to the morphology of the end sac and the labyrinth. In Palaemon, Astacus, and the Brachyura the end sac is distinct and per- ceptible on the dorsal surface of the labyrinth. Frequently, however, the end sac and the labyrinth are either intricately branched or the lumen of both may be subdivided by partitions, which develop as infoldings of the walls
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 121 apparently no uniform structural plan, and some of the most interesting variations elucidated by Marchal relate to the morphology of the end sac and the labyrinth. In Palaemon, Astacus, and the Brachyura the end sac is distinct and per- ceptible on the dorsal surface of the labyrinth. Frequently, however, the end sac and the labyrinth are either intricately branched or the lumen of both may be subdivided by partitions, which develop as infoldings of the walls and obviously increase the surface area of these parts. Unlike that of Astacus, the end sac of the majority is ventrally prolonged into a number of processes which burrow deeply between the convolutions of the labyrinth wall and, in what may be regarded as extreme examples of this interdigitation of the two parts (Galatheidae, Thalassinidea, and Paguridae), the end sac may be so completely embedded in the labyrinth that even its dorsal wall is no longer visible on the surface of the gland. The bladder is also variously modified and, while in many Macrura it is a relatively simple sac, in the Anomura, the Brachyura, and in Palaemon among Natantia it may be extensively and intricately lobed. Marchal's (1892) exhaustive studies indicate that the antennal gland of nearly every decapod species presents its own structural peculiarities and, in this respect, J. lalandii is no exception. From the following account, which is based on dissections and serial sections of the glands of adult specimens, it is apparent that, although there is some resemblance to the organs of Homarus and Palinurus, the parts are not morphologically identical with those of any other species so far described. branch of end sac central cav byr mth. nephrostome central cavity of labyrinth wall of labyrinth ?S§ht*S3~~~^secretory globules Fig. 40. Part of transverse section of antennal Please note that the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
