660 E. PH. ALLIS, 



"4, The fine pore-like openiugs spoken of as 'pinhole' pores by 

 many authors I shall term primitive pores, as illustrating the most 

 generalised form, e. g. certain Elasmobranchs and Polyodon, Psephurus 

 and Acipenser y 



On p. 509 he says: "A series of small branches pass off from the 

 hyomandibular portion [of his main canalj and are distributed over 

 the opercular flap, and terminate in cluster and primitive pores." 



On p. 510: "At the base of the follicle a sensory organ was 

 present, in which uo difference could be seen from those found in the 

 cluster and primitive pores, excepting in size. From their structure 

 and position I regard them as modified cluster pores and synonymous 

 with the sensory follicles which Fritsch speaks of as 'Spalt-Papillen'." 



On p. 512: "Judging from the two examples I have investigated 

 of Polyodon, I should say that it is a feature of rare occurrence for 

 a branch to terminate in primitive pores only, as in PI. 39, fig. 3b." 



He then, on p. 513, gives a description of the histological structure 

 of what he says are the cluster pores of his nomenclature. In this 

 description he says that these pores "agree almost in every detail 

 with the 'Spalt-Papillen' of Fritsch"; and the reader is referred, in 

 support of this, to his fig. 4, tab. 30, which purports to be a longi- 

 tudinal section through one of them. 



Regarding the primitive pores he says (p. 514): "Histologically 

 they appeared to be miniature cluster pores." 



An examination of my several specimens shows, what any careful 

 worker would have concluded, that both in his descriptions and in 

 his figures Collinge has sadly mixed up his organs and pores, and 

 that what he intends to designate as cluster pores are not a special 

 form of surface sensory organ, but simply the surface openings of 

 the several branches of a branching primary tube which leads inward 

 into one of the lateral canals, the whole system of tubes and pores 

 being strictly similar to one of the dendritic systems described by me 

 in Amia (1). 



What the surface organs he shows in his figures 4 and 5 may 

 be is not so easily determined, but it is clearly evident that neither 

 of them can by any possibility represent a simple and normal cluster 

 pore. The so-called section through one of these pores might pos- 

 sibly represent a pore that had, in pushing its way along the outer 

 surface, encountered and partly swallowed, so to speak, one of the 

 several kinds of surface sense organs that Collinge says are found 

 on the head of the fish ; for I found, in Amia (1, p. 506), an example 



