Of the two annex'd _Epistles_, the _First_ gives an account of the dissection of two _Raja's_ or _Skates_, and relates that the Author found in the bellies of these Fishes a _Haddock_ of 11/2 span long, and a _Sole_, a _Plaise_, and nine middle-sized _Sea crafishes_; whereof not only the three former had their flesh, in the fishes stomack, turn'd into a _fluid_, and the Gristles or Bones into a _soft_ substance, but the _Crafishes_ had their shels comminuted into very small particles, tinging here and there the _Chyle_ near the _Pylorus_; which he judges to be done not so much by the heat of the Fishes stomack, as by the help of some digesting juyce. Coming to the _Uterus_ of these Fishes, he takes occasion to examine, with what ground several famous _Naturalists_ and _Anatomists_ have affirm'd, that Eggs are the _uterus_ exposed or ejected out of the body of the Animal. Taking a view of their _Heart_, he there finds but _one_ ventricle, and discourses of the difficulty arising from thence. As for the _Lungs_, he saw no clearer footsteps of them in these, than he had done in other Fishes: but within the mouth he trac'd several _gaping fissures_, and found the recesses of the _Gills_ so form'd, that the water taken in at the mouth, being let out by these dores, cannot by them re-enter, by reason of a skin outwardly passing over every hole, and covering it. Where he intimates, that though Fishes have not _true_ Lungs, yet they want not a _Succedaneum_ thereto, to wit, the _Gills_; and if _water_ may be to Fishes, what _Air_ is to terrestrial Animals, for Respiration: affecting, that whereas nothing is so necessary for the conservation of Animal life as a reciprocal Access and Recess of the _Ambient_ to the sanguineous vessels, tis all one, whether that be done by receiving the Ambient _within_ the body, or by its gentle passing _by_ the _Prominent_ vessels of the _Gills_.