BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 129 
(p. 89) that a greater number of cirripedes have been catalogued from Woods Hole 
than from any of the other stations considered in our table. Only to species each 
have been listed by Whiteaves, Herdman, and the Plymouth laboratory, while 15 have 
been recorded by Graeffe. Six of the Canadian species and 4 of those listed for Plymouth 
are common to our Woods Hole catalogue. 
The barnacles, particularly the sessile forms, are a very baffling group to the tax- 
onomist, and it must be admitted that our local collections have not received the treat- 
ment which they deserve. During the greater part of the Survey dredging separate 
specimens were preserved from each station at which barnacles were taken. A large 
proportion of these specimens were immature, many others were waterworn and imper- 
fect. The small collection made during the summer of 1903 was examined by Dr. H. A. 
Pilsbry, who furnished a list of identifications covering this earlier period. The survey 
was unable to obtain the services of this specialist in determining the barnacles dredged 
during the subsequent seasons of the work.? This task was finally undertaken by the 
senior author of this report, who offers his results with considerable reservation. Atten- 
tion must be called to the frequently reiterated statements of Darwin, the chief monog- 
rapher of this group, respecting the high variability and the indefinite limits of the 
species of Balanus. As evidence of the impossibility of distinguishing these species by 
external characters, he writes (Monograph of the Cirripedia, vol. 11, p. 187): ‘‘ After hav- 
ing described nearly 40 species, and when my eye was naturally able to appreciate small 
differences, I began carefully to examine varieties of B. tintinnabulum, amphitrite, impro- 
visus, porcatus, vestitus, etc., without even a suspicion.that they belonged to these species, 
at that time thoroughly well known to me.”’ It must be added, however, that the case 
is far less difficult to one who deals with a very few species occupying a very limited area. 
Unless certain species which have never been reported from the Woods Hole Region are 
nevertheless common here, our determinations are probably correct in the great majority 
of cases. 
By far the larger proportion of specimens coming from the Survey dredgings which 
have been examined have been referred to Balanus eburneus. Large specimens of this 
species, found upon the bottom of a boat and elsewhere, have been studied carefully, 
with reference both to the internal and external structure of the shell. The same careful 
examination was extended to certain of the specimens coming from the dredgings. 
None of the latter, however, nearly equaled in size the examples taken from woodwork 
in shallow water, and are probably for the most part immature. The longitudinal 
striation of the terga is faintly indicated, or altogether wanting, and the general shape 
of the opercular plates differs from those taken from adult specimens. It must be 
confessed, therefore, that general appearance and the process of elimination have 
led us to our decision in regard to most of these specimens. They are obviously 
not to be referred to Balanus balanoides, for they have a shelly base, and differ in other 
conspicuous ways. Moreover, the latter species is strictly intertidal in its habitat. 
Nor are they to be assigned to Balanus crenatus, B. porcatus, or, indeed, to any of the 
other species which have thus far been recorded from this region. At least one source 
of serious confusion seems to be possible, however. Darwin tells us that “diagnosis 
@ We are indebted to him, however, for the identification of a considerable number of stalked barnacles of the genera Lepas 
and Conchoderma. 
16269°—Bull. 31, pt 1—13——9 
