XX EXPLANATIONS OF THE PLATES. 



c. Hinder part of adult Female specimen, more enlarged, showing Ova 

 lying freely in the Perivisceral cavity and its caudal prolongation. 



d. Ciliated Canal, commencing externally in the larger and smaller 

 Rosette-like disks, a, b. 



e. One of the Pinnulated Segments, showing the position of the 

 Ciliated Canal, c, and its Rosette-like disks, a, b ; showing also the in- 

 cipient development of the Ova, d, at the extremity of the segment. 



f. Cephalic Ganglion, with its pair of Sensory (?) vesicles, a, a, and its 

 two Ocelli, b, b. 



g. Very young Tomopteris, showing at a, a the Larval Antennae ; 

 b, b, the incipient long Antennae of the adult ; c, d, e, f, four pairs of 

 succeeding Pinnulated Segments, followed by bifid Tail. 



PLATE XXIV. (p. 737). 

 circulation in the tadpole (after Whitney). 



Fig. 1. Anterior portion of Young Tadpole, showing the External Gills, 

 with the incipient tufts of the Internal Gills, and the pair of minute 

 tubes between the Heart and the spirally-coiled Intestine, which are the 

 rudiments of the future Lungs. 



2. More advanced Tadpole, in which the External Gills have almost 

 disappeared : — a, remnant of external gills on the left side ; 6, operculum ; 

 c, remnant of external gill on the right side, turned in. 



3. Advanced Tadpole, showing the general course of the Circulation : — 

 a, heart ; b, branchial arteries ; c, pericardium ; d, internal gill ; e, first 

 or cephalic trunk ; /, branch to lip ; g, branches to head ; h, second or 

 branchial trunk ; i, third trunk, uniting with its fellow to form the 

 abdominal aorta, which is continued as the caudal artery k, to the ex- 

 tremity of the tail ; I, caudal vein ; m, kidney ; n, vena cava ; o, liver ; 

 p, vena porta? ; q, sinus venosus, receiving the jugular vein, r, and the 

 abdominal veins, t, u, as also the branchial vein, v. 



4. The Branchial Circulation on a larger scale : — a, b, c, three primary 

 branches of the Branchial artery ; a, cartilaginous arches ; b, additional 

 framework ; c, e, twigs of branchial Artery ; d, f, rootlets of branchial 

 Vein. 



5. Origin of the Vessels of the Internal Gills, g, from the roots of those 

 of the External. 



6. The Heart, Systemic Arteries, Pulmonary Arteries and Veins, and 

 Lungs, in the Adult Frog ; the heart being turned up in the right hand 

 figure, to show the junction of the Pulmonary Veins and their entrance 

 into the Left Auricle. 



PLATE XXV. (p. 744). 



distribution of capillary bloodvessels, as shown in transparent 

 injections (Original). 



Fig. 1. Transverse Section of Small Intestine of Rat, showing the Villi 

 in situ. 



2. Section of the Toe of a Mouse : — a, a, a, tarsal bones ; b, digital 

 artery ; c, vascular loops in the papillae forming the thick Epidermic 

 cushion on the under surface ; d, distribution of vessels in the matrix of 

 the Claw. 



3. Distribution of Bloodvessels in the Cortical Layer of the Brain, 

 showing the manner in which the Arteries, carried-in by the Pia Mater, 

 dip-down into the furrows of the Convolutions. 



