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peripheral utricles are large in specimens belonging to the typical 

 form and smaller in forms coming near to monile and simulans. 

 But just as intermediate stages occur in the outer appearance of 

 these forms, so we often also find specimens with large and small 

 cells intermingled or specimens in which the outer form and the 

 dimensions of the peripheral utricles point against each other. 

 Some examples may illustrate this. 



In Krause's Lagoon on the south coast of St. Croix I have 

 collected (my collections nr. 1484), upon soft muddy bottom in 

 about 1 — 2 meter of water, some Halimeda incrassata forms grow- 

 ing together in a restricted area and of which the fig. 4 a b c 

 give their habit while the fig. babe give surface views of the 



Fig. 5. 



Part of the surface of three specimens figured in Fig. 4. About 80 : 1. 

 The figures indicate the largest diameter of the peripheral utricles in p.. 



peripheral utricles respectively of the same 3 specimens. Regard- 

 ing now the habit of the plants, a and c may be referred to forma 

 typica and b to forma monile; if on the other hand we consider 

 the peripheral utricles, we will find that while these in e are 

 large in accordance with what H. incrassata has after Howe, 

 a has much smaller peripheral utricles bringing it by this fact into 

 the monile-simulans-group, having smaller utricles than the monile- 

 like specimens fig. b, some utricles of which are nevertheless 

 larger than permitted in the monile-simulans-group. Some other 

 specimens (my collections Nr. 1120) collected in the sea west of 

 Water Islands, St. Thomas, at a depth of about 20 meters, 

 point in the same way. Judging from their outer appearance 

 (fig. 6) they come nearest to var. typica, fig. a especially being very 

 typical having a great resemblance with the figure 39 in Mrs. Gepp's 

 monograph of forma typica. The other specimen (fig. b) has some- 

 what broader joints approaching it to var. simulans. If we now 

 consider their respective peripheral utricles (fig. 7) we will find that a 

 has small while b has large utricles. So we see that the specimen 



