442 OCEANOGRAPHY, BIONOMICS, AND AQUICULTURE. 



quotes them as showing that only 7.3 or so species of invertebrates are 

 brought up, on the average, in the trawl net. I happen to know from 

 Mr. Thomas Scott, F. L. S., the naturalist who has compiled the sta- 

 tistics in question, and also from my own observations when on board 

 the Garland on one of her ordinary trawling expeditions, that the 

 invertebrata noted down on the station sheet are merely a few of the 

 more conspicuous or in other ways noteworthy animals. No attempt 

 is made — nor could possibly be made in the time — by the one naturalist 

 who has to attend to tow nets, water bottle, the kinds, condition, food, 

 etc., of the fish caught and other matters — to give anything like a com- 

 plete or even approximate list of the species, still less the number of indi- 

 viduals, brought up in the trawl. I submit, therefore, that it is entirely 

 misleading to compare those Scottish fishery board statistics, which 

 were not meant for such a purpose, but only to give a rough idea of the 

 fauna associated with the fish upon certain grounds, with the carefully 

 elaborated results worked out at leisure by many specialists in their 

 laboratories, of a haul of the Challenger's trawl. Of Dr. Murray's own 

 trawlings in the west of Scotland, I can not, of course, speak so posi- 

 tively ; but I shall be surprised to learn that the results of each haul 

 were as carefully preserved and as fully worked out by specialists as 

 were the Challenger collections. 



Lastly, on the next Liverpool marine biology committee's dredging 

 expedition in the Irish Sea after the appearauce of Dr. Murray's vol- 

 umes, I set myself to determine the species taken in a haul of the trawl 

 for comparison with the Challenger numbers. The haul was taken on 

 June 23, at 7 miles west from Peel, on the north bank, bottom sand and 

 shells, depth 21 fathoms, with a trawl of only 4-foot beam, less than 

 half the size of the Challenger one, and it was not down for more than 

 twenty minutes. I noted down the species observed, and I tilled two 

 bottles with undetermined stuff, which my assistant, Mr. Andrew Scott, 

 and I examined the following day in the laboratory. Our list comes to 

 at least 112 sj)ecies, belonging to at least 103 genera. 1 I counted 120 

 duplicate specimens, which, added to 112, gives 232 individuals, but 

 there may well have been 100 more. This experience, then, is very dif- 

 ferent from Murray's, and gives far larger numbers in every respect — 

 specimens, species, and genera — than even the Challenger deej)- water 

 haul quoted. I append my list of species, 2 and practiced marine zoolo- 

 gists will, I think, see at a glance that it is nothing out of the way; 

 that it is a fairly ordinary assemblage of not uncommon animals, such 

 as is frequently met with when dredging in the Coralline zone. I am 



1 It is interesting, in connection with Darwin's opinion that an animal's most for- 

 midable competitors in tlie struggle for existence are those of its own kind or closely 

 allied forms, to notice the large proportion of genera to species in such hauls. I 

 have noticed this in many lists, and it certainly suggests that closely related forms 

 are conrparatively rarely taken together. 



2 See Appendix, page 454. 



