489 Kneeland's Dissection of . 
lowest reptiles, whose heart consists also of two cavities. In 
fishes, there is no arterial heart, but only a venous auricle and 
ventricle, or the right cavities of the heart; in the Batrach- 
ians the heart is both arterial and venous — the circulation of 
fishes resembles the branchial circulation of the perenni-bran- 
chiate amphibia. 
The circulation in fishes shows that the heart is not the 
sole agent which keeps the blood in motion; its impulsive 
power cannot extend beyond the obstruction the blood must 
meet with in the extremely minute ramifications of the 
branchial capillaries and veins; it seems impossible that the 
vis a tergo, after this resistance, should send the blood through 
the whole arterial and venous system back to the heart; we 
must admit a power resident in the coats of the vessels them- 
selves. Though the system is furnished with pure arterial 
blood, the circulation must necessarily be sluggish. 
The esophagus was very short, 3 inches in length from the 
last branchial orifice to cardia; cut open, 15 inches wide; 
color white, longitudinal fibres distinct. The separation 
between it and the stomach well marked by a band of circular 
fibres, most conspicuous externally. 
The stomach contained a fish 2 feet 6 inches long, @ wolf- 
fish, (Anarrhicas lupus) doubled on itself, and partly digested ; 
with many fragments of echini and shells. The stomach was 
2 feet 9 inches long; cut open, 22 inches wide; the mucous 
membrane without wrinkles, and covered with a tenacious 
slime; in parts, much injected; parietes 4 of an inch thick. 
The spleen was attached to the lower extremity of the 
stomach, resembling an arrow-head in shape, the point down- 
wards ; it was lobulated and convoluted. Length 10 inches; 
width at top 6 inches; thickness 1 inch: there was a prolon- 
gation upwards towards the pyloric orifice, 9 inches long, at 
the top 2 inches wide, and 2 an inch thick; it presented a 
marbled appearance internally ; it contained but little blood, 
though it was dark colored. < 
The pylorus was 7 inches from the bottom of the stomach ; 
