I905- CoLGAN. — Invertebrate Faima oj Skerries, Co. Dublin. 207 



most productive of all, was made in a 15^ -fathom hole about 

 midway between Church Island and Rockabill. 



The survey of the ground thus made may be considered as 

 fairly exhaustive, and if the knowledge gained by a few 

 months of desultor}' shore collecting along the Dublin coast be 

 enough to justify a general statement, I would say that the 

 Skerries sea-fauna is a rather poor one for the county. 

 Special attention was paid to the Skerries mollusca, and, 

 adding together the results of dredging and shore collecting, 

 the total of vSpecies secured, living or dead, was but ninety. 

 Of this number, forty-five, or precisely one half, were found 

 living. 



In notes, such as these, written by a beginner for beginners, 

 a few words on what may be called the technique of coast 

 dredging may be given. The chief points to be attended to 

 are the following : — {a) I,et each cast of the dredge be preceded 

 by a sounding, and a note of the depth found, {b) Except 

 when working in stiff mud or pure sand, it is well to use a 

 long line, say 2^ times as long as the depth of your sounding. 

 This has two advantages — the obvious one, that it ensures a 

 good "bite" of the dredge scraper — the less apparent one, 

 that it prevents a sudden strain on the gear should the dredge 

 foul a rock, {c) Unless your dredge be heavily weighted, tow 

 with the tide or current. If you tow against it with a dredge of 

 ordinary weight, the scraper will be kept lifted off the bottom, 

 and after your men have bent their backs to the oars for a 

 quarter of an hour j^ou will haul up a perfectly clean dredge. 

 A little practice will enable you, by feeling the pulse of the 

 tow line, to learn whether the dredge is scraping or floating. 

 The rope thrills and throbs when the dredge is biting — it 

 keeps a steady tautness when it lifts against a current. 

 {d) Take with you on each cruise three or four galvanized 

 buckets, and a half dozen wide-necked jars — ordinary peach 

 or pine-apple jars, with a cord handle to lift by, will do 

 admirably ; for you must isolate the fruits of each haul, and 

 preserve them living for a time in fresh "sea water if you wish 

 to determine the various species accurately, and note their 

 range in depth. When a full dredge net comes up, and there 

 is no suitable accommodation on board for its varied and 

 possibly valuable contents, then the minor morals of the 

 dredger are apt to go by the board. 



