KEPORT UN* TIT E < ' [RRIP ED. I \ . 145 



the species collected during the cruise of II. .M.S. Challenger, as 1 have neither the long 

 experience of the great monographist, nor the disposal of collections comprising wrv 

 numerous species. 1 It is true we possess at present all the information laid down by 

 Darwin in his monograph ; yet the difficulties with which one has to struggle in 

 determining supposed new species of this genus are very considerable, and may he fairly 

 judged from the curious fact, that in the nearly thirty years which have elapsed since the 

 publication of Darwin's book, only one species (JBakmus armatus, Frit/ Midler) has been 

 added to the genus— a genus of which Darwin knew forty-five species — representatives of 

 which may be collected almost everywhere, and on every coast. Many authors, no 

 doubt, have been engaged in investigating species belonging to this genus, and must have 

 met with forms which could not in a very natural way he classed among any of the 

 species described by Darwin. However, as they had not at their disposal a very rich 

 material for comparison, they must have been left in doubt, and hesitated to introduce 

 it into science as a new species. I think, in most cases, these authors have been right 

 in doing so ; yet I believe that in some cases the publication of a description, illustrated 

 with good figures, may be useful for the development of our knowledge of the genus and 

 the distribution of its species. Should the identity of any species with one described 

 already before be proved afterwards, as may result from a comparative ->ulv of 

 good descriptions and figures, I cannot understand what harm is done to science. 



In consecpience of the admirable completeness with which Darwin has given in his 

 monograph the descriptions of the species, it has been possible, even easy, to identify 

 with certainty seven of the twelve samples of specimens with species already described. 

 Two of these belong to Balanus tintinnabulum, Linn., two to Balanus trigonus, 

 Darwin, one to Balanus Icevis, Bruguiere, and two to Balanus amaryllis, Darwin. With 

 the five remaining groups this has not been possible. Of these three consist of speci- 

 mens belonging to species which I have described as new, but which probably are nearly 

 related to species described by Darwin ; at least it was possible to rank them with the 

 species of Darwin in the sections into which he proposes to divide the genus. The two 

 other samples of specimens, on the contrary, represent two closely allied hut distincl 

 species, which, however, scarcely admit of comparison with species Darwin knew. They 

 form a distinct section of the genus. I was for some time uncertain whether it was 

 not necessary to establish a new genus for their reception. I have not done so, 

 however, because both species come very well within the genus Balanus, as char- 

 acterised by Darwin (compartments six; basis calcareous or membranous; opercular 

 valves sub-triangular). Under Balanus corolliformis I will give the characteristic- of 



1 Of the forty-five species described by Darwin, I only know the following by my own examination -.—Balaniu 

 tintinnabulum, Linn, (different varieties); Balanus psittaeus, Molina, sp.; B tonus, Darwin; Balanus 



Brug.; Balanus perforatus,Bmg.; Balanu ,Darwinj Bala , Darwin; B , da Costa: 



Balanus crenatus, Brag.; Balanus lalanoides, Linn.; i : ; Balanus m Darwin. 



(ZOOL. CHALL. EXP. CART XXV. — 1883.) BTl 19 



