14 



imperceptible manner — as is the case with so many animals. 

 The actual enlargement of the body of the shrimp takes place 

 almost immediately after the shedding of the skin, so that a 

 short time after the moult one would hardly believe that the 

 shrimp could have but recently occupied the <east skin. 



Before assuming the adult form of body the young shrimp 

 passes through several changes of shape. In e aeh stage there 

 are several moults and a gradual increase in the number of ap- 

 pendages takes place. Unfortunately, we have not yet b< en able 

 to secure the younger stages in the life history of this species. 

 but it is hoped that it will be possible to complete the series. 



During the latter part of August and during September larval 

 shrimp (less than a half an inch in length) were fairly common 

 in Calcasieu Pass, being caught with a fine-meshed tow-net. The 

 youngest of these had already assumed the adult form of body, 

 except in a few of the minor details. These immature forms 

 were all perfectly transparent, with the exception of the jet-black 

 eyes. In these stages the growth is rather rapid, but as a com- 

 plete series was not obtained it is impossible at present to esti- 

 mate the time consumed in the transformation. 



OBSERVATIONS ON ADULTS. 



Although it has been impossible to secure as complete a scries 

 of the adults as was desired, still some points of interest have 

 developed from the investigation. It might be noted that in 

 Calcasieu Pass the movements of the shrimp are very erratic; 

 being in large measure dependent upon the conditions of the 

 water and weather. The former is extremely variable in salin- 

 ity, dependent on the amount of rainfall, direction of the pre- 

 vailing winds, etc. On this account it often happens that for 

 relatively long intervals no shrimp will be caught. Then may 

 follow an interval when a few can be caught each day — followed 

 by another period when they are apparently absent from the 

 Pass. 



On account of their extreme delicacy it has been impossible 

 to keep them under artificial conditions, where they may be 

 watched, for any length of time. In this respect they are not- 

 ably different from the "River Shrimp" (Bithynis ohionis), 

 which is much easier to keep alive in a relatively small aquarium. 

 With better facilities for keeping the shrimp alive undoubtedly 



