PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 55 



small a space, being an equal participant in this extensile proi^erty. 

 AVben the jaws were gently opened, they nieasnred 2^ inches across, 

 and 3i inches from the front teeth above to those beloAv; bnt while 

 they i)0ssess this capability of distension, their contractile poicer is no 

 less remarkable^ as may be observed in Plate VII, Fig. 1, which rei)re- 

 seuts the usual appearance. Fig. 2 exhibits the jaws and pharynx more 

 depressed and expanded. Fig. 3 represents an anterior view of tlie 

 same." (P. oG.) 



"The spiracula are of large size, of an irregular oval form, and are 

 unprovided with externally perceptible hranchiostegons rays ; their edges 

 partialiy conceal on each side three brancJiia'. When the sac is con- 

 tracted, these apertures are placed almost under the body, as in the 

 Sphauebranchus, having a narrow commissure between them ; they are 

 placed at about 5^ inches from the snout." (P. 55.) 



"•All the fins of the Ophiognathus are extremely small." (P. 55.) 



" The dorsal Jin, which like the rest is very narrow, and provided 

 with simple rays, commences at about 18 inches from the snout, and ter- 

 minates insensibly upon that slender, tape-like filament, into which the 

 tail becomes converted, and which is continued 20J inches in length be- 

 yond the posterior extremity of the dorsal Jin. About this part of the 

 dorsal liu a few other minute filaments take their growth from it." (P. 55.) 



"The anal Jin commences at the posterior union of the sac with the 

 body, and ends at about 14 inches from the extremity of the caudal Jila- 

 ment:' (P. 55.) 



"In the formatiouof the j»ector«/s there is a peculiarity not mentioned, 

 I believe, in other apodal genera, they being principally composed of an 

 adipose disk, which is terminated and nearly surrounded by a narrow 

 radiated membrane, instead of this latter taking its origin immediately 

 from the body." (P. 55.) 



Dr. Harwood was unacquainted with the description by Dr.Mitchillof 

 Saccopharynx, and compared his fish only with the generally recognized 

 generaof the apodal fishes. He remarked that " although, in the present 

 day, the term ' sea-serpent' would be ill applied to any animal which 

 breathes by means of branchite, yet among such creatures, excluding 

 the Hydrus and Hydrophis, and other true water snakes which inhabit 

 the tropical seas, I doubt if the subject of this communication be not 

 at least as well entitled to the appellation as any hitherto described. 

 From the several genera of animals however nearest allied to it, it 

 offers points of disagreement so important, as to entitle it to a distinct 

 place in classification, and especially from the formation of the jaws, 

 which, with the exception of the apparent want of serpentine inter- 

 articular bones, are truly analogous to those of snakes ; and, secondly, 

 from the possession of an enormous elastic sac, which is seemingly a 

 receptacle for air only. The first of these latter characters appearing 

 to be the one. of all the least liable to vary, I would suggest the term 

 Ophiognathus as applicable to the genus ; its characters are as follows: 



