78 A finals Kiitomoloi^ical Society of America [Vol. Ill, 



several days has been observed to feed on man iininterriijitedly 

 for a period of nearly one hour (59 minutes) at one insertion of 

 its proboseis. 



The bite of the Ctenopsyllus miiscitli, the blind fiea of the 

 mouse, is the feeblest we ha\'e had inflicted from any flea tested. 

 The short weak piercing organs of this species makes a puncture, 

 which is scarcely j^erceptible. In obser\ing the length of time 

 this ilea bites, it is necessary to depend as a guide on the distention 

 of the abdomen with blood rather than the prick of the mandibles. 

 The miisculi seems not able to adapt itself as an induced parasite 

 of man. From a few experiments it appears to live not longer 

 than five days on a human host. 



The Ceratopyyllus aciitiis which proxies a very ready joarasite 

 of man makes its attack even without inducing experimentally. 

 Our data compiled from reports and collections of squirrel hunt- 

 ers shows that this species, as well as the other common squirrel 

 flea, Hoplopsyllus anomalus, will bite man when exposed to their 

 attacks. 



The unusually long rostrum in this flea is presumed to be 

 the cause of its prolonged feeding at one insertion of the mouth 

 parts. This principal is not unprecedented judging from a 

 study of numerous parasites in the insect world. 



The following is the description of the method nf feeding 

 observed in C. acutns. This method is typical. 



The flea when permitted to walk freely on the arm selects 

 in a few minutes a suitable hairy space where it ceases abruptly 

 in its locomotion, takes a firm hold, with the tarsi, projects its 

 proboscis and prepares to puncture the skin. 



A puncture is drilled l)y the ])ricking c])ipharynx, the saw- 

 tooth mandi1)les supplementing the movement by lacerating the 

 cavity foiTned. The two organs of the rostrum work alternately, 

 the middle piece boring, while the two lateral elements execute 

 a sawing movement. The mandibles, owing to their basal attach- 

 ments are, as is expressed by the journal of Hygiene, Vol. 6, No. 4, 

 p. 499, "capable of independent action, sliding up and down but 

 maintaining their relative positions and ]3reser\'ing the lumen of 

 the aspiratory channel." The lal^ium doubles back, the V-shaped 

 groove of this organ guiding the mandibles on either side. 



The action of the proboscis is executed with a forward move- 

 ment of the head and a lateral and downward thrust of the 

 entire body. As the mouth ]xirts are shar])ly inserted, the 



