80 Messrs. Hancock & Attliey on Archichtliys sulcidens. 



long, lies in the middle of the mass, Avith the inner sm*face 

 exposed, and with the alveolar border turned over ; so that 

 several of the teeth are seen, measming from f to | inch in 

 length. This fragment (for, large as it is, it is but a frag- 

 ment) has lost both extremities. 



The anterior extremity of each mandibular ramus is like- 

 wise present on the slab, and has a large laniary tooth in front, 

 and several of the small teeth behind. One of the large teeth 

 is nearly perfect, and measures 2 inches in length, though the 

 extreme apex is deficient, and is nearly an inch wide at the 

 base. The other laniary tooth has been apparently equally 

 large, but merely its stump remains. The largest of the small 

 teeth are about half an inch long ; they appear, however, to 

 have been pretty regular in size, and are placed a little apart 

 from each other. These two mandibular fragments are each 

 upwards of 2 inches long ; so that if one of them be joined to 

 the large portion of the mandible already described, we have 

 the dimensions raised to 12 inches ; but as we have no means 

 of determining how much of the proximal extremity is want- 

 ing, it is difficult to say what was the real length of this for- 

 midable jaw when perfect. Its massiveness, however, is 

 sufficiently evident, as the bone of the anterior fragment is 

 nearly an inch thick. 



The left prtemaxilla is also very well displayed, lying across 

 the large mandibular fragment. It is 3^ inches long, and is 

 If inch wide. The anterior extremity is rounded; and close 

 .to the front margin tliere is, as in the mandible, a laniary 

 tooth, AA'hich is small, however, in comparison with that of the 

 latter ; it is | inch in length, and is proportionately narrow. 

 This tooth is succeeded by about twenty minute teeth, g^ inch 

 long, or thereabouts, which are very regularly arranged at a 

 little distance from each other. 



Mixed up with the above are many other bones, belonging 

 apparently to the skull ; but they are too much broken up to 

 admit of exact determination ; the right prasmaxilla, liow- 

 ever, with its anterior laniary tooth, can be discovered amidst 

 the commingled mass. 



The surface of the more perfect bones exhibits the peculiar 

 tubercular sculpture originally described ; and the characters 

 of the teeth show no variation from (indeed they are ])recisely 

 similar to) those at first pointed out as distinguishing the 

 species. 



Two gigantic jugular plates were obtained at the same time, 

 associated with the above remains, though not on tlie identical 

 slab. We do not hesitate to assign them to ArcJdchthys, not 

 more on account of their association than from the character 



