The North-West Lunar Limb. 257 



Fig. 3. Sporangium ejected, magnified. 



Fig. 4. A thin horizontal section, highly magnified, 

 through the plant just before the rupture of the peridium, 

 showing the structure of the several coats, which do not always 

 follow precisely in the same order, but are sometimes partially 

 suppressed. Two of the sporophores are seen bearing the 

 spores at their tips. 



Fig. 5. Spores magnified. 



Fig. 6. Young plant of Pilobolus crystallinus, magnified, 

 showing the first and second cells, the former of which sends 

 out rootlets below. 



Fig. 7. A plant in which the third cell or sporangium is 

 formed. 



Fig. 8. A portion of the second cell which has thrown off 

 the sporangium, showing the hilum and the protruding par- 

 tition by means of which the explosion has taken place. The 

 second cell in this case has a septum at the point of constric- 

 tion. (These three figures are copied from Cohn.) 



THE NORTH-WEST LUNAR LIMB (continued).— THE 

 ACHROMATIC TELESCOPE.— OCCULTATION. 



BY THE EEV. T. W. WEBB, A.M., F.R.A.S. 



We continue our examination of the districts adjacent to the 

 NW.iedge of the lunar disc. Our last objects were Atlas and 

 Hercules (Nos. 4 and 5). In the region between them and 

 Geminus (No. 2), Franklin (No. 6) may serve as a landmark, 

 having a depth of 8700 feet under the W. end of the ring, 

 and a considerable central hill ; the breadth of the cavity being 

 33 miles. The interior shows but 2° of light in the full 

 moon. 



A great extent of surface, our guides remark, included 

 between Endymion, Atlas, Messala, and Franklin, is almost 

 exclusively occupied by forms which, on account of their boun- 

 daries, may be reckoned as ring-mountains of some import- 

 ance, but, in other respects, can hardly be included in that 

 class. Their interiors are not depressed, or darkened, or 

 distinguished in any way from the external soil ; take away 

 the narrow wall, and no difference remains. The wall itself is 

 usually irregular, open in places, destitute of peaks, and not 

 remarkable for brightness. The inquiry whether these objects, 

 which are not peculiar to this portion of the moon, can have 

 been formed in the same way as the other ring-mountains, 

 must indeed be left untouched ; but it seems evident that if 



