22'6 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 



The larval Ticks were brown, ovate, and possessed three pairs of 

 limbs. They measured 0.6 mm. long and 0.4 mm, broad. As 

 many escaped between the side of the lid and the box in which they 

 were contained, they were transferred into a glass bottle with a cork 

 stopper about an inch broad. The ticks gradually collected into 

 three compact swarms, the largest of which was formed beneath the 

 cork its whole breadth and sometimes, in part at least, nearly a line 

 thick. Another swarm compacted itself in the interval of two 

 crossing twigs about as long and thick as the little finger, and the 

 third formed a dome-like mass about one-third of an inch broad, on 

 one of the twigs. From time to time they partially scattered, and 

 then collected again in the same close swarms. 



Exhibited to the Academy this evening, September 23, the young 

 Ticks appear yet to be alive and in good condition, though the>- 

 have eaten nothing. Fruit and other parts of plants have been 

 placed at their service, but they do not even approach them. On 

 two occasions some were placed on Prof. Leidy's arm, but they did 

 not seem disposed to attach themselves. 



The mature Ticks present two well marked varieties, probably 

 the two sexes. In the one there is a conspicuous white spot on the 

 back immediately behind the head, sharply defining a thoracic 

 shield. In the other there is no distinct appearance of the .shield, 

 but fainter white streaks lie outside of its position and extend in 

 four feebler streaks on the abdomen, apparently defining the intes- 

 tinal coeca. In the former the genital aperture is central between 

 the anterior two pair of limbs ; in the latter it is between the second 

 pair of limbs. The blood-filled specimens that laid the eggs accord 

 with the former. 



He was unable with certainty to refer our common Tick to it> 

 proper place among the multitude that have been named, but sup- 

 posed it to be tho^ Amb/yomma americaniim of Koch, indicated earlier 

 by Linnaeus as Acanis aincricayuis. There is much uncertainty in 

 the knowledge of our Ticks. Koch ascribes nine species to North 

 America, referring them to the genera Amblyomvia, Ixodes, and Der- 

 7Haccntor, the last belonging to Pennsylvania. Saj^ describes six 

 other species of Ixodes, Packard two, and Rile}- one. Say's Ixodes 

 scapula? is, which the author .says is common in our fore.sts and at- 

 taches itself to various animals, seems to approach closely the Beach 

 Haven Tick, and Riley's Ixodes bovis also seems to accord pretty 

 well, judging from the figures and characters given. If, however, 

 the latter at maturity is half an inch long, as stated by Packard, it 

 is most probably a different .species from the Amblyovima amcrica- 



