THE OREGON NATURALIST. 95 



here in groups adhering to slabs of the food in suitable pieces for ma*ticalion. 



smoked massive quartz, intimately These five j.ws work on hinges of a 



associated with fine mica crystals and cartilaginous nature and can be worked 



crystals of brilliant hematite of excellent separately or in unison at the will of the owner, 



quality. Prof. Wood, who is an excellent authority on 



It is a matter of regret that the crystals natural history tells us that the skeleton or 



are all small few if any will cut gems of shell is composed of a large number of pieces 



over two carats in size. or plates whose juncture can only be seen by 



E. H. HARN, examining the shell from the interior. By 



Henry, IN- U. holding one of the cleaned shells so the light 



can penetrate the interior tiirough the aperture 



SEA URCHINS the plates can plainly be seen. 



Externally the shell presents an unbroken 



Probably there are no animals of our marine ^^^^face, with the exception of the protuberences 



waters less understood by the general public .^^ere spines were located. The urchins retain 



than the common star fishes, or five fingers as t^eir original shape during growth and as the 



some call them, and the sea urchins of our ^.^^^u^y ^^^^^^ composing the shell is added 



coasts. It is of the latter especially this article ,egularly to the edges of these plates, the 



is written. With the exception of timse living gbbnlar shape is not lost by the enlarging of 



on the sea coast, and those, who duiing the i^e shell 



summer frequent the shores and are interested j have before me a specimen of StroK^v/ocen- 



in natural history the public in the interior tro/us/ranciscanus from the Pacific coast, and 



have little knowledge of them. To the loiterer ^^^^^^ beautiful symmetrical proportions are 



alone the beach it is not an unusual sight to see 1,1,1 r m » > u .-r 1 1 



=■ . ° pleasmg to all lovers, of JNature s beautiful works, 



a number of these queer animals thrown upon .,,, . ,, ■ ., . • 1 



^ . ' 1 lus shell IS rather warty in appearance nearly 



the beach by the receding tidal waves. Tli.s , ,- .. 1 .. .. r 



■' ° 13 inches in circumlereBce at largest part of 



is especially true of the common star fishes. , ,, „„ ■ .• .u . r r .u 



•^ ■' . . shell. I he projections on the outer surface of the 



Those studiously inclined, will take adv;intae;e , ., , , , • 1 . j /-» 



/ . =" shell show where the spines were located. On 



of this by securing several for examinati n and , ■ r 1 i r 1 



-' " this siiecimen I have counted 20 rows 01 large 



^ " ^' projections and 35 rows of smaller ones running 



Scientists have placed the sea urchins in the , , n i -.u 



from base to apex, ail arranged with 



mathematical precision. Interspersed through- 

 out these larger rows are many smaller ones. 

 Between the rows of these projections thousands 

 of small openings or pores can be noticed. 

 The spines are peculiar in structure and pre- 



, . , , r . sent some interesting details. Each spine is 



with a thick growth of spines, comnletelv , ,.,,,. , 



, , T , 1 , r movable at the will of Its owner, and moves on 



sul>-kingdom of Radiates. Star fishes are 

 also included in this sub-kingdom and all 

 whose bodies internally and externally are 

 radiate in arrangement, that is whose parts are 

 similiar around a vertical axis. Tlie urchin 

 when first found in its natural state is covered 



concealing the beautiful skeleton or frame work 

 underneath. There is only one opening into 

 this skeleton, the mouth being located in the 



a ball and socket joint, the cavity at the end 

 of the spine, fitting exactly the round project- 

 tion on the shell. The spines are fastened to 



middle underneath. The bony laws or , . . , ... 



. . , , , „ . . the ball by a thin tenacious membrane which 



"Aristotle s lantern as it is commonly , , , ,. 



called is compofed of five separate ]iarts, 

 armed at the points with sharn knife-like ap- 

 pendages. These jaws can be brought together at 

 the point so that the five little knives can cut up 



allows them free movemeiit. After death this 

 membrane becomes dry and fragile anrl is 

 easily broken and the spines drop off, hence 

 the difficulty of amateurs in kee]iing urchins in 



