PLATE X. 



MARE CRISIUM AND NEIGHBORING PARTS OF THE MOON. LICK OBSERVATORY. 

 ENLARGED TO TWICE THE SCALE OF PLATES I TO VIII. 



This plate shows the region about the M. Crisium, the most circular of the seas. It is not 

 completely illuminated, a portion of the western boundary being beyond the light. 



In the M. Crisium the most noteworthy feature is the ruined character of its shores as if by 

 the melting action of the lava of the field. There is an obscure step or bench along the shore of 

 the mare as if the lava had subsided, as in the larger vulcanoids. 



Northeast of the M. Crisium is a large crater, Cleomedes, with a small pit on its south wall 

 and two craters and a cone on its floor; next farther to the northeast a vulcanoid known as Burk- 

 hardt. Note that this has two deformed craters beside it, one to the northwest, the other to the 

 southeast. These features seem to have been produced by some compressive action due to the 

 formation of Burkhardt. East and southeast of this point there is a remarkable confusion of 

 deformed vulcanoids. Near the middle of the M. Foecunditatis lie two small craters known as 

 Messier, whence extend to the southeast two nearly parallel bands of light. The pits of this pair 

 of vulcanoids have been thought to change their shape in a lunar period. By some early observers 

 the bands were supposed to be artificial objects, and one astronomer suggested that they were built 

 by the selenites to signal the people of the earth. There are several ridges on the mare to the 

 westward of Messier. 



The large vulcanoid to the southwest of Messier with a central crater, just beyond three 

 smaller pits of nearly the same size, is Langrenus, next south Vendelinus, yet farther south 

 Petavius. The first and last of these show distinct benches on their inner walls. The last has 

 many pits on its crest. 



On the southern margin of the M. Nectaris is Fracastorius, another vulcanoid with the sea- 

 ward side of its wall demolished by contact with the maria, though it is still traceable ; there are 

 several other like instances about this mare. 



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