868 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



of the yolk (y) and the thin yolk-sac (ys). The oil-globule (og) seems to lie in a pocket 

 in the cortex of the yolk, as an equatorial line crosses over it, yet it is also enveloped 

 by a complete protoplasmic covering (p). The gall-bladder (gb) occupies, in the upper 

 posterior portion of the liver, a position just at the angle where the ventral embryonic fin 

 (ef) joins the yolk-sac. As first shown by De Filippi,* the gall-bladder of the larval 

 Clupea Jlnta lies also behind the yolk ; the liver, however, does not in this instance pass 

 downward. The pectoral fin (pf) is somewhat fan-shaped, very thin and membranous, 

 and stands erect ; while a chitinous clavicle (el) is fixed by a longitudinal lateral attach- 

 ment. The long intestine, with a distinct rectal portion, curves downward a considerable 

 distance from the yolk, and cuts off, by the anal protrusion (a), a ventral fin-area about 

 one-third the length of the inferior embryonic membrane. The lumen of the alimentary 

 canal is spacious and the walls much folded, but that of the oesophageal section is very 

 much diminished. A valve or cincture marks the commencement of the rectum (hg). 

 The segmental duct (sg) is plainly seen passing from a convoluted pronephric portion 

 (with oval glomerulus, gl), with an undulating course to a spacious urinary vesicle (uv), 

 which opens close to the anus (a). The notochord (nc) is fairly straight, but in the 

 mid trunk it ascends by a gentle curve and gently bends round, to end between the 

 posterior limits of the two eyes. It has the usual large irregular cellular structure, and 

 presents a distinct perichordal sheath (pes). The heart (h, PL XIII. fig. 5) is fully 

 formed, showing a rounded ventricle, which gives off, in front, a narrow bulbus directed 

 upward, and behind receives the large vase-shaped auricle, opening into a wide sinus 

 venosus. The pericardial chamber (pd) is large, and its floor is entirely free from the yolk. 



The oral and branchial cartilages are well developed (PL XIII. fig. 5). The mouth is 

 widely open on emergence, and water freely enters. Only tremors of the mandible, 

 however, are noticed. The mandible (mn) is as usual a massive cartilage with an 

 enlarged articulating extremity, joined by two cartilages from above, the anterior or 

 quadratopterygoid (ptg), and a more massive hyomandibular (hm), which springs by a 

 large base from the floor of the ear-capsule (au). Four acutely curved branchial cartilages 

 (bra) are present, and the long hyoid cartilage (hyd) ends in a copula, which projects as 

 a nodular eminence on the under surface of the mouth. The maxillary elements cannot 

 be made out, but the front margin forms an overhanging upper lip. The parts of the 

 brain are well marked, — the fore brain (fb), on the lower anterior face of which are 

 laterally placed the nasal sacs (ol), the pineal gland (pn), and the large dome-shaped mid 

 brain (mb), with the cerebellar fold (cb) behind. The eyes have a silvery lustre, with a 

 black pupil. A few black pigment-corpuscles occur over the anterior superior curve of 

 the eye, and this region shows a fine green shade like malachite. 



The structure of the ear is very complex, and the two otoliths seem to lie in the same 

 anterior ampulla. 



The marginal fin (ef) commences very gradually between the ears, i.e., posterior to 

 he cerebellum, and it does not become very wide, although its depth is somewhat increased 



* Ann. des Sci. nat., 3 me s6r., vii. p. 66, pi. i. fig. 1. 



