368 Alexander Pethunkevitch, 



nor female reacts in any way to tlie presence even of such large 

 things as a mouse or the human hand. It is interesting to observe 

 the difference in behavior between a Bugesiella and a Lycosa nidi- 

 cola when both are placed in the same box. Bugesiella pays no 

 attention to Lycosa no matter at what distance they are from each 

 other. Quite different Lijcosal This beautiful hunting spider will 

 run without hesitation toward Bugesiella until it is about 20 to 

 10 centimeters from the latter, when it invariably stops and no 

 teasing can force it to go on in the direction of its powerful enemy. 

 I have repeated the experiment time and again and always with 

 the same result. An insect that having come close enough to touch 

 Bugesiella, by some chance escapes her attack, is in no further 

 danger from pursuit. Bugesiella does not pursue and has no instinct 

 for pursuing its prej^, an instinct which would be of no avail without 

 Organs of perception. But the most instructive evidence is furnished 

 by the courtship. The male, if he once loses contact with the female, 

 continues his courtship alone, beating helplessly with his front legs 

 on the ground and Walking aimlessly about, unaware of the female 

 he is courting even if she is not farther than a centimeter from 

 him! The sudden change in his behavior when he happens to touch 

 her again, even with his bind legs, is so marked, that no other 

 explanation is possible than that both sexes are entirely dependent 

 upon their sense of touch. 



This sense in all spiders is very highly developed, but especially 

 the tarantulas are noted for their hairy appearance. The body and 

 legs of Bugesiella are thickly clothed with hairs of several different 

 kinds. Some are very thin and plumelike, others much stiffer, while 

 still others may be regarded as regulär bristles. The base by which 

 they are attached to the skin is also variously structured, being 

 characteristic for each kind of hair. But since it is not my purpose 

 to study the morphology of the hair, I do not give a detailed de- 

 scription. Suffice to say that every Single hair is connected with 

 the nervous System by means of one or more terminal sense cells 

 and a sensory nerve. Sections through the skin show the heavy 

 Chitin to be perforated by innumerable canals running from the 

 hypoderm to the base of each hair. The terminal sense cells are 

 located not in the hj^podermis but in the canals of the chitin, about 

 half way between their outer and inner openings. The sternum is 

 so heavily covered with hair that it looks almost like a brush. Hair 

 is, however, absent in six places called the sigilla which represent 



