of the Fishery Board for Scotland. 



203 



If the two smallest fishes be included in the second group, the difference 

 between the latter and the next older one is 69 '8mm. 



Some other collections of Lumpenus were measured, the largest being 

 one procured off Burghead in thirty-two fathoms on 1st April, and which 

 comprised 365 specimens. These, after being preserved in formaline, were 

 measured by the Laboratory attendant, and the measurements are 

 included in the Table appended. On preparing a curve, however, it is 

 apparent that either the series was irregularly represented, or the 

 measurements faulty, since the divisions between the groups are not 

 marked. Four series, however, at least, seem to be indicated. 



With regard to the age of these groups, it is necessary first of all to 

 decide as to the period of spawning, about which little is known. In 

 specimens taken off the Shetlands on 31st August and 4th September, 

 the females, ranging in size from 234mm. to 286mm., had large ovaries, 

 with large eggs from l'lmm.to l'44i[nm. in diameter, the ovaries them- 

 selves measuring from 25mm. to 35mm. long.* These specimens were 

 evidently on the eve of spawning. 



In a collection procured in the deep water off Kinnaird Head, Moray 

 Firth, on 23rd January, the sizes ranging from 153 mm. to 284 mm., the 

 ovaries were small and lax, and the tissue contained a great number of 

 small dark-brown bodies scattered throughout them, apparently eggs or 

 blood in the process of disintegration and absorption ; they appeared to 

 be spent. The same condition was noted in the ovaries of the specimens 

 taken off Burghead on 1st April. On the other hand, in a few specimens 

 procured in the Firth of Forth on 16th August, measuring from 236 mm. 

 to 283 mm., the eggs were well developed, the largest ranging in diameter 

 from 1*1 mm. to 1*4 mm. ; the yolk spheres were large and small oil- 

 globules were present. 



From these observations it may be concluded that Lumpenus spawns in 

 the late part of the autumn or the early part of winter, and it is probable 

 that the eggs — which appear to be demersal — do not hatch until early in 

 spring, which may therefore be taken as the period from which to date 

 the rate of growth. 



Looking to the rate of growth between the series as shown above, it is 

 probable that the smaller specimens in May, measuring 123, 127, and 128 

 mm., were a little over one year of age, the specimen obtained off the 

 Shetlands at the end of August, 84 mm. in length, being probably six or 

 seven months old. The average size of Lumpenus when one year old is 

 obviously less than these sizes, the smaller forms having escaped capture. 



The information as to the size at which maturity is reached is very 

 scanty, the number of specimens approaching ripeness which were 

 examined having been small. In August the smallest in that condition 

 were 236, 239, 241mm., and they evidently belonged to the same group 

 as the third (197-263mm.) represented in the curve for the May 

 measurements. The probability therefore is that Lumpenus 

 spawn when three years of age. It may be noted that many 

 of the largest specimens procured are males. This sex therefore does not, 

 as with the flat-fish, grow at a slower rate after maturity than the females. 

 A Table of measurement of some of the collections is appended. 



* Nineteenth Ann. Report Fishery Board for Scotland, Part III., p. 287. 



