54« CELLTJLAmiD^. 



agrees. The smallness of the avicularia^, and the fact 

 that they are so placed as to be partially concealed by 

 the spines, may explain their having escaped the notice of 

 such accurate and experienced observers. 



In S. reptans these lateral appendages are clearly dying 

 out. They are only found on some of the cells, and, as 

 I have said, are generally extremely small, mere pygmies 

 as compared with the similar structures on such a form as 

 S. scruposa. They are placed close to the top of the cell, 

 and just behind the triplet of spines. From their reduced 

 size they do not extend down the side of the cell, and are 

 therefore very inconspicuous and liable to be overlooked. 



On the other hand, the pedunculate avicularia, placed 

 at the bottom of a certain number of the cells in each 

 internode, are most fully developed, and attain a compara- 

 tively gigantic size. We may no doubt trace a con- 

 nexion between their vigorous condition and the dwindling 

 of the lateral appendages, which must be due to their 

 comparative uselessness, and therefore disuse ^. 



These large avicularia are situated on the inferior por- 

 tion of the cell, below the apertvire ; and though not con- 

 nected with evo'y cell, there is a certain definite and 

 constant number on each internode f. Between the joints 



* Suiitt has remarked that " on the whole the rule holds good for this 

 genus" {CcUularia, including Scrupocellaria'), "that the more the lateral 

 avicidaria are developed, the less are the anterior " (Kritisk Forteckn. part 

 iii. p. 305, footnote), a remark which I can fully confirm ; and I believe 

 that the converse is also true. We have a remarkable illustration in 

 >S. ferox, Busk, a species from Bass's Strait, which possesses a very large 

 pedunculate avicularium, occupying almost the whole front of the cell 

 below the aperture, with a long curved mandible, whilst its lateral avicu- 

 laria arc rudimentary and quite insignificant. The relative development of 

 the two classes of avicularia is much the same in S. diadema, Busk. 



t Busk speaks of the front avicularia in this genus as "disposed in a 

 special tract along the middle of the branch or internode." This is 

 the case in his C. ftrarhnoideii, which also wants the lateral avicularia ; and 

 to this species the name Cauda must be restricted ; his remark docs not 

 apply to B. reptans. 



