144 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ei 



ber of lateral spines of the carapace varies from two to nine. The 

 spines are not necessarily paired. A specimen may have four spines 

 on the left side and nine on the right side. The areolae of the speci- 

 mens from Cave Spring Cave range from 33.3 to 36.6 percent of the 

 total length of the carapace. The Shelta material measures 38'.5 

 to 40.5 percent. The crayfishes of this subspecies from other caves 

 in this region range from 36.1 to 39.5 percent. The blind cray- 

 fishes of the Mammoth Cave region also vary from cave to cave. 

 The areola of typical C. pellucidus is 36 to 41 percent. Shelta Cav- 

 ern and Huntsville Spring Cave specimens are similar in having 

 very short apical spines of the antennal scale. Other caves yield 

 specimens with long apical spine similar to C. pellucidus. 



In spite of the variations listed above, the marked similarity 

 of these varieties causes me to place them all in the subspecies 

 C. pellucidus australis. 



No doubt C. pellucidus australis of the South bears the same 

 affinity to C. pellucidus pellucidus as does the Gamharus pellucidus 

 testa Hay (1893) of the North. 



Ecology and distribution. — This crayfish is found throughout the 

 caverns of the limestone region in northern Alabama. According to 

 Dr. Walter B. Jones the presence of crayfishes in caves seems to be 

 correlated with the presence of blind fishes and aquatic insects. In 

 caves without connections with the surface, food chains develop 

 among the animals present. Mr. Hubricht suggests that bat guano 

 may provide some food for crayfishes. 



Dr. Jones writes, "Shelta Cavern is a rather large cave with sev- 

 eral underground streams and rather large underground lakes. I 

 have never seen muddy waters in Shelta Cavern. There is scarcely 

 any outside trash entering the passages. 



"Cave Spring Cave is a typical underground stream although there 

 are some rooms scattered about here and there. That cave is 3,050 

 feet long, or longer, and the water is quite cold. At times the stream 

 is muddy and completely fills many parts of the passage. In fact, 

 one cannot go very far back into it in wet seasons. The crayfish 

 fauna is rather abundant, and I could easily have taken a gallon of 

 specimens. Cave Spring Cave, as does Shelta Cavern, has white fish. 



"Huntsville Spring Cave is about % mile long with a low ceiling 

 and a deep-channeled stream. It is reached by a vertical manhole in 

 a street near the center of the city. The roof and the floor are irregu- 

 lar. The stream is spring-fed and permanent, having an average 

 flow of 39,000,000 gallons a day. The cave is located under the city 

 of Huntsville and is full of narrow passages, crevices, and loose rock. 

 No fish have been found there. 



