278 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



year of continuous study is the minimum prerequisite for any sort 

 of competence in the systematic study of the group. 



Only well-preserved and accurately labeled material should be 

 utilized. 80 or 90 percent alcohol (which may include 1 percent of a 

 stock formalin solution) is suggested for initial preservation, and the 

 collector should avoid overcrowding the jar with crayfish. Too many 

 of the crustaceans in one container dilute the preservative and cause 

 maceration of the worms. Isoprop3'l alcohol may be used, full 

 strength, for preservation, although it is usually only about 70 percent 

 in strength, and fewer crayfish can be placed in a given volume. 



Material so preserved may be left indefinitely in jars with the host 

 animals or isolated and restored in tiny shell vials plugged with cotton 

 and packed in larger jars. Each collection may be assigned a different 

 number which relates the specimen vial to collection data entered in 

 a book or on index cards. Either the collection number alone, or a 

 tiny label printed with a fine pen, will suffice to be included in the vial. 

 Cataloging systems are limited only by the ingenuity of the individual, 

 but in practice, the simpler a system the better. 



In curating material, one removes the crayfish from the jars with 

 enough vigorous shaking to dislodge any worms that may be still 

 attached to the exoskeleton. It is also desirable to search the branchial 

 chambers and gill filaments for gill-inhabiting forms, either b}^ cutting 

 open the carapace with stout scissors or by extracting the giUs with a 

 curved-tip forceps inserted between the carapace and bases of the legs. 

 The gill material is then placed in a dish of alcohol and picked apart 

 under a low-power dissecting microscope. This done, the majority of 

 the alcohol is decanted carefully from the collecting jar to avoid loss 

 of any of the bottom sediment which is then transferred to a flat glass 

 dish and examined with a dissecting microscope. 



In a given collection there may be but a single species or as many as 

 four, each representing a different genus. As a rule these species will 

 differ enough in habit form to facilitate easy separation, although in 

 some cases identification even to genus is difficult until slides are pre- 

 pared. In practice it is advisable to select good specimens of each 

 form for mounting, all of which can be processed together. From the 

 flat-bodied forms such as the species of Xironogiton and XironodrUus, 

 it is desirable to choose specimens which are least curled or twisted. 

 From the cylindrical forms, which normally preserve in a sort of 

 crescent-shaped profile, one should select those which are most nearly 

 straight in the plane of the dorsoventral median body axis. Since 

 Imowledge of the jaw form is important, it is useful to prepare at least 

 one specimen flattened dorsoventrally, or to remove the head from a 

 specimen and split it along one side to allow for subsequent spreading 

 at the time of mounthig. This operation is easily done \vith a fine- 



