STUDY OF HYDROZOA. 73 
Note.—Stephanocyphus mirabilis Allman is the type of a new order 
of Hydrozoa called by Allman Thecomeduse. The animal permeates 
and is parasitic in sponges. Although a Hydrozoan, it is not a 
Hydroid, and cannot be referred to any of the existing orders of the 
Hydrozoa. The chitinous tubes which permeate the sponge-tissue are 
united toward the base of the sponge, and constitute a colony of zooids. 
In many respects it is said to resemble the Campanularie. 
VIEW OF THE CLASSIFICATION OF THE HYDROZOA, 
Siphonophora. 
es . (Physalia.) 
f ; i { ( : 
i Mee 7 ; 
} Discophora, 
\ (Aurelia.) | 
Hydroidea. 
(Hydra.) 
| 
Hyprozoa. 
Laboratory Work.—The common Hydroids, such as Coryne, Sertu- 
daria, etc., may be collected from sea weeds or the piles of wharves 
between tide-marks, while the meduse may be obtained by the 
hand-net, or tow-net from a boat. The meduse especially abound 
in eddies off points of land where different currents of the sea meet. 
Towing is most effectively pursued after sunset and early in the even- 
ing, when the sea is calm, and the jelly-fish swim near the surface. 
‘They should be placed in the jars by inverting the net in the water of 
the jar, and examined at once, as many will have perished by the next 
morning. Jelly-fish can also be reared in roomy aquaria, in which 
plenty of air is introduced by running water. 
The larger meduse, such as Aurelia and Cyanea, should be sliced 
in sections in order to study their gross anatomy, and portions snipped 
off with scissors to be examined with the microscope. The animals of 
Sertularians, Coryne, etc., can be studied alive in animalcule-boxes 
and growing-cells. The coral stock of Millepora was examined by 
Moseley in ground sections. _ ‘‘ Portions of the living coral were placed 
in absolute alcohol, chromic acid, and glycerine ; portions were further 
treated with osmic acid and transferred to glycerine or absolute alcohol. 
Fragments of the hardened coral were afterward decalcified with 
hydrochloric acid, and the residual soft structures were either mounted 
entire for examination, or cut in the usual manner into fine vertical 
and horizontal sections, which were then stained with carmine or 
magenta. The specimens hardened in osmic acid, and decalcified after 
subsequent immersion in absolute alcohol, yielded the best histological 
results.” 
