6 Mr. H.J. Carter on the Conjugation of 



Now it so happens that in one of the earliest states that was 

 presented to me of the conjugation of Amphora, the endochromes 

 were joined together in the form of the figure 8 (fig. 32) , and I 

 could not help coming to the conclusion that the endochromes 

 of both frustules passed into one sporangium at first, instead 

 of directly into two, as in .Eunotia, and then became divided 

 afterwards ; or, that this was an accidental occurrence. If this 

 is the normal process in both Cocconema and Amphora, then it is 

 easy to conceive how the sporangial frustules become opposite 

 each other in both instances, viz. by the division of the united 

 endochromes taking place either parallel or transversely to the 

 longitudinal axes of the conjugating frustules. We have some- 

 thing analogous to this in Meloseira and Aulacoseira, where the 

 axis of elongation of the sporangium is parallel with the filament 

 in the former, and at right angles to it in the latter; with the 

 line of division of course the reverse in each *, that is, with the 

 filament in Aulacoseira, and across it in Meloseira ; correspond- 

 ing in the former to Amphora and in the latter to Cymbella. 

 Facts however are wanting to prove this conjecture. 



I need hardly call attention to the difi*erence in the size and 

 forms of the conjugating and sporangial frustules which are 

 represented in the Plate, or again remind the reader of what 

 Mr.Thwaites has stated, viz. that the sporangial frustules, though 

 very difi'erent from the conjugating ones at first, eventually assume 

 a form very similar to them ; this is effected by fissiparation, and 

 equally applies to the endochrome as to the frustule. It is well 

 seen in figs. 23-31. The relative size of the forms represented 

 in the Plate has been preserved as much as possible, and each 

 figure is taken from nature, with the exception of No. 2, which 

 to supply a deficient link has been constructed upon No. 3 and 

 other observations. 



Amphiphora alata (?), Kg. PI. I. fig. 33. 



There are at least two species of this genus abounding in the 

 back-waters of the island of Bombay, and as they do not appear 

 to have been studied much in their living state, and have con- 

 stantly come under my observation, I propose offering the fol- 

 lowing remarks on that one, which, if not identical with, is very 

 nearly allied to the A. alata of Kiitzing f- 



Frustule. — Oblong, truncate ; primary surfaces closely approx- 

 imated, lateral surfaces produced laterally and so compressed as 

 to form a thin edge, which, being constricted in the centre, 



* Thwaites, loc. cit. vol. i. p. 161. pi. 11. A 2, B 2. 

 t Species Algarum, p. 93. I regret that I have not his figures to deter- 

 mine this satisfactorily. 



