GEAF ZU SOLMS-LAUBACH— MOXOGEAPII OF THE ACETABULAEIE/E. 



dichotomous sterile hairs, and if they have fallen off, the scars likewise remain on 

 much smaller swellings of the stem. This regular alternation of cap and wliorl of 

 hairs was excellently illustrated hy Harvey [12, p. 40], and later descrihed hy Cramer 

 [5, p. 24]. 



The scars of the whorl of fallen hairs are easily distinguished from those of the cap. 

 While they have the form of hrq^d oval figures, not touching each other, with a point in 

 the centre — the original opening now closed uj) — those of the disc-chamhers are pressed 

 together laterally, elongated, and marked with a narrow central perpendicular slit. In 

 order to explain the mode of origin of this very peculiar appearance I examined such 

 caps as were over-ripe and beginning to disintegrate. Tliis resulted in the observation 

 that the hreaking-up was caused hy the splitting of the partition- wall between the 

 vestibule and the basal portion of the cap-chamber, but that simultaneously (through a 

 farther thickening of the membrane of the stalk) a deeper division is attained in which 

 the new lamellge, produced by apposition, cut off transversely and bridge over the cavity 

 of the vestibule. It is the lumen of the vestibule, thus cut off and much narrowed 

 laterally by thickening, which, after the decay of the lamella originally covering the 

 partition, appears in the form of the perpendicular slit described. Since i had only 

 a small amount of material of Acetabular ia crenulata suitable for determining this 

 question, I was unable to follow out the stages in the cutting off of the vestibules ; in all 

 the caps still in situ which I examined there was nothing of this to be found. I have 

 never observed this peculiarity at least in typical specimens of A. caraibica, in every 

 point nearly related to A. crenulata \ Kiitzing's ^. caraihica, var. calyculata, of which 

 this is the distinguishing point, is probably only the true A. crenulata. 



The possession of several successive caps on the same shoot is otherwise a rare anomaly 

 in the genus. Exactly this condition of A. crenulata was found on a specimen of 

 A . Caly cuius, Quoy et Gaimard, by Askenasy. On another shoot of this species the same 

 author found two successive caps separated by several hair-whorls. They have been 

 observed by Bornet and Woronin in a few specimens of A. mediterranean and by myself 

 in a single specimen of A. Mobii (Plate IV. fig. 1). But in the latter case it differed from 

 A. crenulata in that the two caps were immediately one above the other without the 

 intervening whorl of hairs. How it would be in this respect in the case of A. mediter- 

 ranea I have been unable to decide from lack of material. 



Let us now examine the genus Acicularia, d'Archiac, which has been hitherto known 

 only in a fossil condition. It was established by dMrchiac on small longish bodies, 

 pointed at one end, broad and emarginate at the other, found in the Paris Eocene, which 

 consist of calcium carbonate and are surrounded with numerous cavities opening outwards. 

 Both d'Archiac and Michelin referred them to the Bryozoa, and Reuss at a later date did 

 the same, while Carpenter placed them among the Eoraminifera. To the original species 

 A. pavantina, d'Archiac, lleuss added another similar form from the Austrian Miocene, 

 viz. A. miocenica. The circumstance that these lime-spiculse were occasionally found 

 together radially disposed, and that the remains of radial partition-walls w^ere to be 

 recognized, led Munier-Chalmas to remove them from the animal kingdom and, with rare 

 divination, place them with the AcetabulariecB. This conjecture, which had little to 



SECOND SERIES. — BOTANY, VOL. V. C 



