PARORCHIS ACANTHUS, A NEW TREMATODE. 345 



Parorchis acanthus, the Type of a new Genus 

 of Trematodes. 



By 



Williniii ]\icoll, m.A., B.8c., 



Gatty Marine Laboratory, St. Andrews, 



Witli Plate 21. 



The form with which I am about to deal is one possessing 

 several distinctive features of importance, and for that 

 reason I have thought it worthy of special consideration. 

 The following account is by no means exhaustive, but it is 

 sufficient to place the species beyond any doubt of recog- 

 nition, and to establish its claim to be regarded as the type 

 of the genus to which it belongs. 



Parorchis acanthus, mihi. 



1906. Zeugorchis acanthus, gen. and sp. n. Nicoll, 



Ann. and Mag. Nat. Hist. (7), xvii, p. 519 — 

 522, pi. xii, figs. 4, 5 ; xiii, figs. 6, 7. 



1907. Parorchis acanthus, Nicoll. Ibid (7), xix, 



p. 128. 



The original description of this form as Zeugorchis 

 acanthus was made from two preserved specimens found in 

 the bursa Fabricii of a Herring-gull (Larus argentatus). 

 It is incomplete and erroneous in parts. I have since 



