26 
It will be noted that the highest level above low-water datum at which the 
mussels survived until July 31st was 19.2 feet in the sunny exposed location 
(7.e., south pile wharf series) and 21.0 feet in the shaded location (7.e., below 
beams wharf series). It will be seen; also, that the number surviving at any 
level was small. This was due to two causes, viz., the mussels were set out on 
shingles which furnished unsuitable surfaces for firm attachment and they were 
unprotected from the depredations of the Purpura, which wrought great havoc 
among them, especially at the lower levels. 
TABLE X. 
Showing upper limit of survival of Mytilus edulis L. during the first south pile wharf series 
experiment in 1919. 
13Y LoXe) "ei ie re yh ena AEST Pah AL) BE. (Cl. Dal VE. | Fas Giles seieaa ie K1. 
Height in feet above low water datum.} 9.5/11.1/12.7/14.2/15.9 17.6119.2121.0/22.6 24. 3/26.0 
Rea length in mm. when set out el a) Palais Gee 
Pty Aeon pe oe ok ole Pee vio werd LO DAD 22 12 1D 10 5 O p51 1 eee ee 
No. set out on block July 4...:. ge ...| ? ? > ? ? P7859 | 57ers 
5 ip, [On Se Stan eee an a oa ‘90 | 17 (16 (49 ?)| P| |e |e eee 
jill ee PP PPP 
28 Maral . acer egrets: eee 25rd Te 22 CoM sese Wh ee ap eer ene 
oan ULE ae eee ene 20} 12 | 14 | 28 | 11 | 48 | 22 | 21 | 43 [rae | 54 
ate Near pleclessacpeit ste ees eee 1 Ree G7] 24s el AS roe |= Oia) MO een Ses 
ec z ves le* SS |g oe IE IE Ea | a | | | rs 
Ze Biotal eae rate. Salaries oy sae 21 | 15 | 205). 32 4, 12) 52°|'25 4 21 || 43124 aee 
£2 (On Block. ccisehenceel Bl alia 2) opel 3-5: ol neat 
Be inehiocde) kk he este 
See | ed (8 oe a (a ae a ae | 
a ABEL Se ete spree ed Bie rk oe 5.38 War 8 Oy 218. | Salk O02 erie 
Pitiecjaanee July eee nt Os Heel ct a Bae <7 so as Sa e!  Pal e 0 ae 0 
Note.—Numbers marked * included a large proportion of dead mussels. 
So few of the first sets survived until July 31st that two other sets (blocks 
Nos. A3, B3 to 13 and A4, B4 to L4) were put out in the same locations, but on 
the type of blocks used in the anchored pole series. In addition to the grooves 
on the surface to which the mussels attached these blocks had holes bored in 
these surfaces to provide greater protection. The blocks within the zone of 
activity of the purpura (7.e., up to 17.6 feet above low-water datum) were also 
protected by wire cages. The results obtained in the second south pile wharf 
series are given in Table XII. 
40 
