Howe: Phycological studies 91 



parvula"^ Solms, described from material collected by Mme. 

 Weber-van Bosse at Macassar, Celebes, and vicinity; yet the 

 West Indian plants in our opinion cannot be well identified with 

 either one of these East Indian forms, specimens of which we have 

 seen through the generosity of the collector. Of the character of 

 the calcification in y^ff/rt^/z/rt-r/^ exigua, '$>o\ms states"! am un- 

 able to say anything more definite as to the calcification of the 

 sporangial membrane of this species than that the few sterile speci- 

 mens from Macassar were uncalcified. The others came under 

 my observation only after lengthened treatment with acid. How- 

 ever, their sporangial rays are so widely separated from each other 

 that a union of these by means of lime-incrustation is scarcely 

 likely." In the single specimen of A. exigua that we have seen 

 the rays are entirely free^ spore -bearing, and are well incrusted 

 with lime over their whole surface except for their apices and 

 small areas here and there which have been left naked and smooth 

 by an evident flaking-off of the lime-crust. The aplanospores in 

 this specimen are 82-91 fi in diameter. From Acetahtdaria exigua 

 Solms, Acetahtdum pusUlwn differs in its usually smaller size, in 

 the more coherent, less pointed, commonly more numerous rays, 

 which are broadest at two thirds or three fourths their length in- 

 stead of near their middle, and in the smaller coronal" processes, 



ly 



ments. 



In Acctabularia parinda Solms, the calcification of the disc 

 is confined to the contact faces of the rays and to a narrow 

 sharply defined zone involving the bases of the rays and flanking 

 the coronal processes ; the projecting interradial lime-buttons, de- 

 scribed and figured by Solms, are apparently not always present, 

 and such, so far as we have observed, are wholly wanting in Aceta- 

 bulum pusilbnn. Acetabulum pitsilliim further differs from Aceta- 

 htlaria parvnla Solms in its commonly smaller size, in the often 

 fewer, usually pointed, instead of rounded-obtuse or subtruncate- 

 obtuse, rays, which are broadest at two thirds or three fourths 

 their length instead of at their extreme ends, and in the smaller 

 coronal processes (22-35 /^ e/^. 42-5 5 Z'). which in nearly all cases 

 bear two instead of three or four ( ! ) hairs ; the aplanospores of 

 the East Indian plant are still undescribed. 



* Lo€. at. 29. //. 2. f. J, J. 



