Lockington.] 88 [April 6, 
of interlocking plates radiating from near the center to the circumference 
of the vault. 
This observation persuades me that it is not improbable that the original 
plates of Lepidocentrus eifelianus, described and figured by Johannes 
Miiller, from the Hifel limestone of Rommersheim, which were detached 
plates associated with spines similar in nature to those just described and 
borne upon similar tubercles, were plates from the vault of a true Orinoid 
like Arthroacantha, 
We have here a possible clue to a relationship between true Crinoids 
and Perischeechinide, which is worth following up by any paleontologist 
who may have good specimens of these rare forms of Echinodermata. 
EXPLANATION OF PLATE. 
Arthroacantha Ithacensis, noy. gen. et sp. 
Fig. 1.—Calyx and part of arms, showing spines arising from plates of 
salyx, vault and arms, 
Fig. 2.—Diagram of the elements of the calyx. 
Fig. 3.—Enlarged view of part of the vault with spines attached. 
Fig. 4.—Enlarged tubercle (b) and base of a’ spine (a), showing pit in top 
of former and in base of latter. 
Fig. 5.—Spine about three times natural size. 
Fig. 6.—Arm-plates. (a) A few joints of arm; external view, showing 
tubercles and jointed pinnules. (6) Section of same. 
Fig. 7.—Section of the stem at a distance from the calyx. 
Fig. 8.—Lower termination of stem. All enlarged except Fig. 1 
The Role of Parasitic Protophytes. Are they the Primary, or the Secondury 
Cause of Zymotic Diseases? By W. N. Lockington. 
(Read before the American Philosophical Society, April 6, 1883.) 
Parasitic unicellular organisms or microbes, usually considered to belong 
to the vegetable kingdom, are found, in some form or other, in the interior 
of the higher animals, both when in their normal state of health, and when 
suffering from disease. 
Certain rod-like forms have received the generic name of Bacillus ; 
spherical globules that of Micrococcus, while other shapes have been en- 
titled Vibrio, Bacterium, and Oladothrix. The idea of those who gave 
these titles was evidently that each of these forms is actually distinct under 
existing circumstances, 
Nomenclature has even proceeded farther than this, since such binomials 
as Bacillus anthracis exist. 
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