PENTASTOMA T^NIOIDES. 395 



surface smooth, but in the larval condition {== Pentastoma denticulatum) furnished with 

 numerous rows of small, sharply -pointed spines ; length of the female from three to four 

 inches, with a breadth extending to nearly half an inch ; length of the male only from 

 eight to ten lines, vrith an extreme breadth of one line and a half; genital aperture of 

 the female at the extremity of the tail, that of the male being situated at the front part 

 of the abdomen in the middle line ; mode of reproduction oviparous, with a subsequent 

 and complete metamorphosis. 



In the sexually-mature condition this parasite infests the 

 nostrils and frontal sinuses of the dog and wolf, and occasionally 

 also, though very rarely, the same cavities of the horse and sheep. 

 In the pupa and larva state it sometimes occurs in the abdominal 

 and thoracic cavities of the human body ; much more frequently in 

 various herbivorous mammals, such as the sheep, deer, antelope, 

 peccary, porcupine. Guinea-pig, hare, and rat ; and, according to 

 Creplin, it has also occurred in the domestic cat. In these animals 

 and in man the so-called Pentastoma denticulatum usually occupies 

 little cysts within or upon the peripheral parts of the liver and 

 lungs, but I have occasionally found them free in the cavities of the 

 abdomen and pleura. 



The anatomical investigations of Blanchard, Van Beneden, and 

 T. D. Schubert, have incontestably shown that the Pentastomata 

 have little or nothing in common with the Cestoda, in which order 

 of helminths they were formerly classed ; but that, on the contrary, 

 these parasites belong either to the Acarine or Lernaean Arthro- 

 poda. They constitute, in short, a genus which may be regarded 

 as osculant between the Acaridee and Lernsead^, leaning, perhaps, 

 more strongly to the former, in which family I have accordingly 

 placed them. Leuckart, who has written a profound memoir on 

 the Pentastomes,* elevates them into a distinct family, comprising 

 one genus of eighteen species. Here, however, I have no space to 

 foUow him either into minute anatomical details, or into the various 

 interesting questions which a consideration of the metamorphoses 

 and affinities of the Pentastomata naturally suggests. Still less can 



* "Bau und Entwioklungsgesohichte der Pentastomen; nach untersuchungen 

 besonders von P. tcenioides und P. denticulatum." Leipzig and Heidelberg, 1860. 



