OF ARTS AND SCIENCES. 291 



of the anterior termination of the notochord below the level of the 

 eyes. We find also along the body a large patch at the posterior 

 extremity of the stomach, a second at the end of the intestine near 

 the vent, with a smaller patch between this and the anterior one, and 

 a third prominent patch extending across the body half way between 

 the vent and extremity of tail, with a couple of smaller spots in front 

 and one behind this patch. In the stage of Plate XIII. fig. 3, the 

 opening of the mouth is still inferior, the pectorals have greatly 

 increased in size since the preceding stage, the body has much 

 lengthened, the vent is placed about half way between the anterior and 

 posterior extremity, and the embryonic fin folds are comparatively 

 much narrower. In a stage but slightly older (Plate XIII. fig. 4) the 

 chromatophores are larger and more prominent, the pectorals have 

 increased in size, the head has increased in length, the mouth is more 

 anterior, the yolk bag has become much reduced, and the heart and 

 alimentary canal have greatly increased in size. In the next stage 

 (Plate XIII. fig. 5), the fourth day after hatching, the young Fish 

 measures about 4™™ in length, and has greatly changed from the 

 preceding day. The opening of the mouth is anterior, the branchial 

 rays have been formed, the heart is divided into chambers, the stomach 

 proper has greatly increased in size, and the intestine is better special- 

 ised than in the younger stages. The muscular bands appear well 

 defined above and below the notochord, embryonic caudal rays are 

 quite distinct, the permanent pectoral rays are blocked out, and the 

 pigment cells are reduced to the three large patches described in the 

 previous stage and a few smaller cells round the eyes and on the head. 

 A small but prominent pigment spot has made its appearance near 

 the end of the notochord on the lower side of the body. The stages 

 intermediate between Plate XIII. fig. 1, and Plate XIV. fig. 1, were 

 not traced. In Plate XIV. fig. 1, the caudal is well developed, show- 

 ing but a slight trace of its ganoid lobe. The head is much larger, 

 the body comparatively stouter, the mouth anterior, the branchiae well 

 developed, and important changes have taken place in the size of the 

 stomach. In the next stage (Plate XIV. fig. 2), measuring 6™" in 

 length, the snout has become more pointed, and the body is quite 

 broad and comparatively much flattened. 



The spinal apophyses, of which a few could be seen in the pre- 

 ceding stage, are large and well developed, the dorsal and ventral 

 muscular bands have become most prominent, there is a trace of the 

 origin of the ventrals, the anal and dorsals are separated from the 



