. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 79 postero-lateial adductor muscle. They are probably equivalent to the minor abductor of Astacus which, however, tapers towards its insertion by a short tendon on the outside of the mandible. Flexores palpi {a, b, c) The three-segmented mandibular palp is joined to the body of the man- dible by a pliable arthrodial membrane and is moved actively in front of the mouth by one extrinsic and two intrinsic flexor muscles. As in Astacus, the palp has no extensor muscle
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 79 postero-lateial adductor muscle. They are probably equivalent to the minor abductor of Astacus which, however, tapers towards its insertion by a short tendon on the outside of the mandible. Flexores palpi {a, b, c) The three-segmented mandibular palp is joined to the body of the man- dible by a pliable arthrodial membrane and is moved actively in front of the mouth by one extrinsic and two intrinsic flexor muscles. As in Astacus, the palp has no extensor muscles, but Schmidt (1915) has suggested that the elasticity of the arthrodial membrane probably provides the necessary opposing force. Flexor palpi a is relatively strong and originates medio-ventrally on the posterior inner face of the body of the mandible beneath the medial part of the anterior adductor muscle. It tapers towards its insertion by a short tendon on the medial proximal edge of the first segment of the palp. The last segment of the palp of Astacus is furnished with a flexor muscle, but in Jasus there are two such muscles, flexores palpi b and c which bend the two distal palpal seg- ments. Each arises in one segment and is inserted medio-ventrally in the proximal part of the next segment. (d) The first maxilla (Fig. 20) As it plays an important part in the manipulation of the food, this small flat appendage has well-developed muscles, most of which are thick and cylindrical and cause strong rotation of the appendage on its slack arthrodial membrane. endopodi te adductor endopo_ depressor uter endite ner endi te. Fig. 20. Muscles of left first maxilla, dorsal view. Promotor This is a fairly stout muscle attached by a small tendon laterally on the anterior fascia below the fused paraphragms of the fifth and sixth cephalic segments and close to the sternal region. It passes somewhat obliquely outward across the base of the appendage and is inserted dorso-laterally in the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
