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Show 170 MR. F. G. PARSONS ON THE [Jail. 14, Epilrochleo-anconeus.-This is present in all the Myomorpha ; it is supplied by the ulnar nerve. Pronator Radii Teres.-This muscle agrees with the description given of it in other Rodents ; in Mus barbarus and Cricetus it is inserted into the second quarter of the radius, while in all the other animals examined it goes into the middle of that bone. Cricetomys resembles Sciurus in possessing a supracondylar foramen, but in it the pronator teres does not rise from the supracondylar arch, as it does in Sciurus. Flexor Carpi Radialis.-The attachments of this muscle were normal in all cases. In the Vole, and, to a lesser extent, in all Rodents, the tendon of this muscle is bound down to the flexor surface of the radius by a fibrous pulley just below the attachment of the pronator radii teres. Palmaris Longus.-The muscle is present and large in Cricetomys, Cricetus, Microtus, Georychus, Bathyergus, Mus rattus, Siphneus, and Heteromys; it is inserted into the palmar cartilage or ossicle and into the fascia of the palm. In Rhizomys and Gerbillus it is only inserted into the fascia, while in Myoxus it is absent. In Mus barbarus it is developed as a slip from the surface of the flexor sublimis digitorum, an arrangement which recalls that found in Coelogenys and Xerus. Flexor Sublimis Bigitorum.-In all the animals examined, except Mgoxus, this muscle rises from the internal condyle and forms the flexor perforatus for the 2nd, 3rd, and 4th digits. In Myoxus it also goes to the 5th digit. Milne-Edwards describes the slip to the 2nd digit as a distinct muscle in Siphneus. Flexor Carpi Ulnaris.-This muscle has the usual attachments, except that in Rhizomys and Bathyergus the origin from the internal condyle is wanting. The tendon is specially thick in Georychus. Flexor Profundus Digitorum.-The deep flexor of the fingers is composed, as in other Rodents, of two superficial heads from the internal condyle and of two deep heads from the flexor surfaces of the radius and ulna. A small slip is given off to the pollex from the front of the tendon formed by these heads in Cricetomys, Gerbillus, Microtus, Mus barbarus and rattus, Myodes, Georychus, Bathyergus, and Rhizomys. In Myoxus, Cricetus, and Siphneus (Mdne-Edwards) no tendon goes to the thumb. In Bathyergus the fibres derived from the different heads were traced downward through the tendon, and it was found that the two condylar heads join together to form the superficial part of the tendon, which gradually winds round the outer side to eventually become deep. When the tendon divides into its ultimate five slips for the four fingers and the thumb, each slip receives fibres both from the condylar and the radio-ulnar origins. This twisting of the tendon reminds one of the arrangement of the fibres of the tendo Achillis \ There are usually four lumbricals which arise from the flexor surface of the tendon at or before its point of division. 1 Author's paper, ' Journ. An;it.' vol. xxvii. p. 414. |