1882.] MR. W. A. FORBES ON THE GREAT ANTEATER. 301 



bones ; running then forwards and outwards, they pass beneath and 

 to the outside of (in a sternal view) the conjoined ducts, and then 

 ascend to fan out and form the muscular bulb. The more anterior 

 of these fibres are inserted into the internal and upper part of the 

 combined ducts, and cease there. The most posterior, on the 

 contrary, completely encircle the ducts, running inwards over the 

 ducts, and then, recurving on themselves, ascend on the deep aspect 

 of the ducts, to be inserted on the stylohyal bone for the greater 

 part of its length, not, however, extending to either of its extremities. 

 Along the anterior (free) border of the ascending part, at the point 

 where it is in contact with the ducts and the deep part of their 

 muscular ring, is developed a strong tendinous edge {s.h. m. t), the 

 " commissural tendon " of Owen. 



The muscular fibres inserted on this and attached to the stylo- 

 hyal (ceratohyal of Owen's nomenclature) are described by that 

 author as the " cerato-hyoideus," whilst Pouchet more correctly 

 applies to it the name of " stylo-hyoideus," the rest of the muscular 

 arrangement here described forming, as already stated, the ''con- 

 strictor salivaris" of both authors. 



It appears to me that the whole muscle may be more correctly 

 considered as the stylo-hyoideus, which has developed this remark- 

 able course round the submaxillary ducts in order to aid the 

 ejaculation of the saliva therein contained by the constriction, on 

 contraction of the muscle, of their walls between the circularly-dis- 

 posed fibres surrounding them and the tendon developed on its 

 anterior margin. 



In the genus Tamandua^ (Plate XV. fig. 2) there is no special 

 muscular envelope developed round the ducts in this position. The 

 most posterior fibres of the mylo-hyoideus (m.h') arise from the 

 posterior end of the stylo-hyal bone, running inwards and forwards, 

 and blending internally with the genio-hyoid. To this point also run 

 backwards and inwards the fibres of a narrow flattened muscle (s.h. m), 

 which crosses the hyoid origin of the mylo-hyoid superficially, and, 

 as it arises from the stylo-hyal bone, must be considered to represent 

 a stylo-hyoideus. At the point where it meets the genio-hyoid and 

 mylo-hyoid, all three muscles become closely connected together, the 

 gtylo-hyoid developing here an anterior tendinous edge (s.h. /«. t). 

 Between this tendon and the conjoined mylo-hyoid and genio-hyoid 

 run the three ducts of the submaxillary gland, so that contraction 

 of these muscles here also serves a purpose similar to that produced 

 by the more speciahzed arrangement found in the larger species. 



[P.S. July 13, 1882. — I have found the disposition of the salivary 

 ducts and the arrangement of the stylo-hyoideus muscles exactly the 

 same as those here described in a third specimen of Myrmecophaga 

 just dead.— W. A. F.] 



EXPLANATION OF PLATE XV. 



Fig. 1. Dissection of the left suprabyoidean region oi Myimeco'phaga jtihaia, 

 to ehow the course and relations of the siylo-hyoideus muscle. 



^ Cf. Duveruoy, Mem. Strasb. 1630, "Memoire sur la langue" &c., p. 3. 



