810- The American Naturalisi. [September, 



20 were observed in Lake St. Clair. In the case of the inlarid lakes, 

 collections were made from the shore only. The most abundant pelagic 

 species are Polyarthra platyptera Ehrbg., Anuraea cochlearis Gosse, 

 and Asplanchna priodonta Gosse, which agree, in this respect, with 

 the condition found in European lakes. 



The Internal Anatomy and Relationship of Pauropus. — 

 According to Peter Schmidt, whose preliminary paper appeared in the 

 Zoologiseher Anzeiger, 1 the internal anatomy of Pauropus allies it most 

 closely with Polyxenus among the Diplopoda. The absence of trachea, 

 of malpighian tubes and of a circulatory system, together with the 

 presence of a rather complicated genital apparatus in the male, seem to 

 show that it is very degenerate. That it belongs along with the Dip- 

 lopoda — a fact that has been questioned — the presence of the ovary 

 below the intestine, of the genital openings in the third body segment 

 behind the second pair of legs, and of only two pairs of oval append- 

 ages, abundantly testify. The biramose antennae may possibly be ex- 

 plained by a comparison with the sense papillae at the end of the 

 terminal joint of the Diplopod antenna, the more readily, too, since, 

 according to Schmidt, the distal portions of the rami, the geisseln of 

 Latzel appear to be finely ringed and not segmented. 



Several peculiarities are interesting. The mid-gut is without a mus- 

 cularis and its epithelial cells are filled with rhomboid crystals with 

 double refractive powers. The supra- and sub-oesophageal and the 

 first body ganglia are fused into one mass which is pierced by a very 

 short fore-gut. The small processes on the first segment represent rudi- 

 mentary legs and possibly function in respiration like 

 the abdominal sacs of Thysanura, Symphyla and cer- 

 tain Diplopods. The sense organ of the antenna?, 

 the globulus of Latzel, consists of an outer and inner 

 capsule with the intervening space filled with a fluid. 

 The whole is surrounded by ten or twelve bristles 

 while the nerve passes into the inner capsule and ex- 

 pands into a nail-like head. (Fig: 1.) Fig. 1. 



The female genital apparatus consists of an unpaired ovary lying, 

 beneath the intestine, an unpaired receptaculum seminisand an oviduct 

 opening to the exterior by an unpaired opening to the one side of the 

 median line in the third segment. In the male there is an unpaired 

 testis above the intestine, a complicated pair of ducts, a pair of seminal 



x Zur Kenntniss des inneren Baues des Pauropus huxleyi Lubb. Zool. Anz., 

 XVII, 189. 



