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



Clupea harengus, L., and remarks on Clupeoids. — The youngest stages (A) of the 

 herring were those hatched in the laboratory, 6th March 1885, and they measured 7 mm.* 

 They are distinguished by their elongation, by the situation of the anus, which lies behind 

 the commencement of the posterior sixth of the body, by the vesicular yolk, and by the 

 ovoid condition of the yolk-sac. The mouth is conspicuous in some, in others it is not 

 visible, therefore it is probable that there is diversity in regard to the degree of develop- 

 ment at the period of hatching, as indeed the variable length shows. The pectorals stand 

 at a slight angle to the body. The marginal fin is dilated in the caudal region. These 

 specimens seem to be larger than Dr Meyer's Baltic herring, which were only from 5 '2 

 to 5*3 mm. in length, and the same length is given by Kupffer. 



Considerable progress had been made on the second day (stage B), for good examples 

 measure 8 mm. , and the body is less filmy. The yolk-sac is elliptical rather than ovoid, with 

 the marginal fin carried forward on its surface posteriorly. A slight opacity occurs above 

 and below the tip of the notochord. An opaque internal process also appears some distance 

 in front of the anus. The mouth is a mere fissure, for the mandible is not much developed. 

 A faint black pigment-line runs along the ventral border from the yolk-sac to the anus. 



The next stage (C) is represented by examples caught in the mid- water net at 4 fathoms 

 off the East Rocks, 29th March 1887. These Clupeoids are now about 10 mm. in length. 

 The general outline of the fish is still much elongated, the snout is blunt, the eyes 

 large and prominent, with a silvery lustre and a black arch of pigment superiorly. The 

 mandible projects considerably in front of the snout. The otocysts are so large and pro- 

 minent that the body appears to come off abruptly from the anterior region. The pectoral 

 fins are similar to those in the foregoing stage, but the marginal fin has disappeared from 

 the body, and a small elevation occurs on the dorsum (noticed even in examples two days 

 old), some distance in front of the anus. The caudal arises about midway between the 

 anus and the tip of the notochord (which is quite straight). Its outline is spathulate, 

 and there are many embryonic rays. The ventral pigment now forms a dotted line on 

 each side, between the pectoral region and the anus, and some specks also appear on the 

 ventral border of the notochordal region at the tip of the tail. The anus is at the com- 

 mencement of the posterior sixth of the body. 



This form is evidently considerably older than the second, as the advances in the 

 head, the hyoidean, branchial, and mandibular regions show. The branchial arches project 

 freely ventrally. It is probable that it is at least a week or two older, a period which 

 would correspond with the deposition in March, and those captured appeared to be about 

 the same age, and were in great abundance amongst Sagittse, Medusae, Zoese, exuviae of 

 Balani and other forms. Meyer observes that free herrino; at the age of a month are 

 17 to 18 mm. in length, so that the foregoing, according to this author, would be consider- 

 ably less than a month old. It has to be borne in mind, however, that there is great 

 variation in the growth of fishes. 



* The form of these was much more elegant than the larval herring represented by Mr Cunningham, Trans. Roy. 

 Soc. Edin., vol. xxxiii. pi. i. fig. 3. 



