570 ALLIS. [Vou. XII. 
to derive that muscle from it, that it may safely be considered 
as its homologue. The strong aponeurosis in the upper part 
of the muscle in Amia corresponds to the tendinous, upper 
part of the muscle in Scymnus, and in the young of Amia the 
muscle is connected or associated with the adductor mandibulae 
much more than with the palatine arch, as it is in the adult. 
In Galeus canis Addy was not found. It is, however, probably 
represented in one of the two spiracle muscles. 
In Chimaera and Acipenser Addy cannot with certainty be 
identified in the descriptions given by Vetter, but it may be 
represented in Chimaera by Cs4, and in Acipenser by the upper 
tendinous part of Cs: and Csz. In the one specimen of Aci- 
penser that I examined, a young Acipenser ruthenus about one 
foot in length, this upper part of Cs: and Csz seemed to bea 
tendinous formation into which the muscle fibres of the lower 
portion were inserted, rather than a tendon of that lower por- 
tion. Its position does not differ greatly from that of Addy in 
Heptanchus, and if it be that muscle, it would account for the 
unusual insertion, below and in front of the eye, of Cs: and 
Cs2, the lower portions of which represent, in Acipenser, that 
part of the superficial constrictor from which the geniohyoideus 
in other fishes arises. This part of the constrictor is, in Acan- 
thias (No. 124, Fig. 3, Pl. XIV), inserted at the hind edge of 
the lower jaw, mainly into a fascia that covers and arises from 
the lower portion of the outer surface of the adductor mandi- 
bulae, just as Addy arises, in the same fish, from the upper 
portion of that surface. Slight changes only in the insertions 
of these muscles in Acanthias would bring about the arrange- 
ment found in Acipenser. 
b. Levator Maxillae Superioris, Csd:, and AddB. 
The levator maxillae superioris, in Heptanchus, arises from the 
occipital part of the skull under the projecting and overhanging 
postorbital process. Immediately behind it, and partly contin- 
uous with it, is another muscle, called by Vetter Csd1. Both 
muscles run downward and forward, and are inserted on the 
inner side of the upper jaw, the hind muscle covering with its 
