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



stage was found on the 11th October 1886, so that either the spawning period is pro- 

 longed, or two spawning periods occur. 



On the 7th May 1884, a form still further advanced was caught in the tow-net in 

 Aberdeen Bay, its total length being 27 mm. This would therefore correspond in some 

 respects with the progressive growth of the foregoing, though the irregularity in this 

 respect of marine as of fresh- water forms renders great caution necessary. The dorsal fin 

 has now nearly reached a vertical line from the tip of the pectorals, but not quite, and it 

 shows short fin-rays anteriorly. From the vent backward both dorsal and ventral fins 

 have long rays — much longer than in the previous stage. The hypural crescents are 

 crossed by the caudal fin-rays. The snout has grown still further in front of the eyes, 

 and the head more closely resembles that in the adult. The branchial processes now 

 present well-marked papillae, and the gill- rakers are longer than in the previous stage. 

 The former come off nearly at right angles, but the rakers slant differently. A 

 membranous marginal fin appears ventrally from the anus about a third along the 

 abdomen, and less distinctly somewhat further forward. 



While the larval forms occur in March, it is necessary to state that others much 

 larger are captured by the mid- water net at the same time. Thus, on the 29th or 30th 

 March, three were obtained — 18, 22, and 25 mm. in length respectively — such being in 

 all probability the young of the previous season. Day concludes that they spawn in the 

 autumn and winter months. He found in A. tobianus the " milt and roe " advanced in 

 August and September, while Thompson states they deposit spawn at the end of July, 

 but in some places they do so during the winter. Couch, again, considers the end of 

 December the most common period, so that Day is of opinion that they continue 

 spawning in the sand through the last few months of the year. 



Again, an example, 33 mm. in length, was caught in the mid- water net on the 10th 

 July 1887. Finely ramose pigment-corpuscles now stud the dorsum for a short distance 

 behind the pectorals to the base of the tail, and the head and opercular regions have also 

 an increased number. The tip of the snout is likewise similarly pigmented. The fleshy 

 base of the pectorals has become much less in proportion to the distal region, from the 

 increase in the length of the fin-rays and the consequent alteration in the shape of the 

 organ. The pectorals, indeed, seem to attain their maximum at this stage. The 

 elongation of the snout and the prominence of the tip of the mandible are also features 

 of note. In regard to the pigment of this and other stages, it may be observed that 

 considerable differences exist, according to the condition of the corpuscles. When 

 contracted they form mere points — leaving the dorsum comparatively pale, whereas in 

 expansion they constitute finely ramose pigment-areas with a central black point. 



At 45 mm. in length (August) the snout still further elongates, and the hollow in the 

 turbinal region disappears. From the increase in length and bulk of the body the pectoral 

 fins do not have the same proportional size as formerly. The other characters are those 

 of the adult. 



Unknown Larval Fish (D). — An unknown larval fish (PI. VIII. fig. 1) was pro- 



