347 



The male pleopods are subject to some variation. The lateral margin of the 

 exopod of pleopod I may or may not have a reentrant angle about one-third 

 the distance from tip to base. The inner distal angle of the basis may be 

 rounded or rectangular. The serration of the inner margin of the exopod of 

 pleopod II is almost imperceptible. The medial margin of the basis of pleopod 

 I is produced basally into a lobe which is folded over ventrad. 



The medial, distal, scaly area on the third segment of pereiopod VII is 

 replaced by rows of minute spines, doubtless representing scales. There is a 

 marginal double row of these spines, one-third the length of the margin, and 

 two shorter sub-marginal rows rather distinctly separated from each other. 

 The indentation of the medial edge of the fifth segment is sub-basal, not median 

 as in linearis. 



Type. — A male from Katama, Marthas Vineyard, Mass., is in the collection 

 of the Boston Society of Natural History (Crust. 1146). Co types, male and 

 female, are in the same collection (Crust 1147) and in the author's collection 

 (M223). 



Occurrence. — This species appears to be exclusively an inhab- 

 itant of salt marshes and similar situations. I have taken it in 

 company with Armadillidium vulgare, Porcellio scaher, Philoscia 

 muscorum, and once with Armadilloniscus ellipticus. 



Distribution. — Mass.: Woods Hole, Katama on Marthas Vine- 

 yard (type locality), and between Shimmo and Polpis on Nan- 

 tucket. 



Remarks. — The present species differs from linearis in being 

 stouter, lacking spines at the tip of the telson, and having 

 tubercles only on the first three pleon segments. Trichoniscus 

 thielei lacks tubercles on the second pleon segment. Halophilus 

 may be further distinguished from both linearis and chavesi by 

 details of the pleopods I-II in the male, 



Literature Cited. 

 Blake, C. H. 



1930. Redescription of Armadilloniscus ellipticus (Hargar) with some 

 account of its habits. Occas. Papers Boston Soc. Nat. Hist. 5 : 279-284. 

 Fig. 1-11. 

 Herold, Werner. 



1929. Beitrage zur Kenntnis der Trichonisciden I. Die Untergattung 

 Spiloniscus Racovitza in Deutschland und in Ostbaltikum. Zool. 

 Jahrb. Abt. Syst. 57: 215-252. Fig. 1-10. 



Kesselyak, Adorjan. 



1930. tJber Isopoden. Zool. Anz. 91: 50-66. Fig. 1-25. 

 Norton, A. H. 



1909. Some aquatic and terrestrial crustaceans of the State of Maine. 

 Proc. Portland Soc. Nat. Hist. 2: 245-255. Fig. 1. 



