THE NAUTILUS. 6 



Philomycus costaricensis (Morcb), variety a. 



Length (in alcohol) about 11.5 mm., width of sole 1.5 mm.; very- 

 pale ochreous, the mantle with rather sparse grey floccose markings, 

 and a pair of (subdorsal) grey bands, irregular in outline and more 

 or less interrupted, consisting in fact of crowded grey spots. Res- 

 piratory orifice about 2 mm. from anterior end of mantle. Sole with 

 a distinct median groove, evanescent anteriorly. Penis-sac cylindri- 

 cal, the apical end curved over and turned downwards, so that the 

 whole structure looks like a compressed interrogation mark. Jaw 

 broad, strongly arcuate, about 1170 fj, across, and 320 deep in 

 middle, the outer thirds wholly without ribs or evident striae, the 

 inner third with six broad ribs, distinct above, but failing below. 

 (The young specimen shows better developed ribs, five in number.) 

 Teeth about 21-13-1-13-21, the central ones strongly tricuspid, the 

 lateral cusps small. The teeth agree in general character with 

 those of P. dorsalis, as figured by Binney, differing however in the 

 relatively longer basal plates, the short and broad central teeth not 

 much more than half as long as the plate, certainly not over three- 

 fifths as long. The interesting thing about this species is that it be- 

 longs strictly to the group of P. hemphilli and P. secretus, found in 

 North Carolina. It is apparently P. costaricensis (Morch), at least 

 as described by W. G. Binney (Ann. N. Y. Ac. Sci., May, 1884) 

 from material collected in Costa Rica by Gabb. Our slug differs 

 from Binney's account in the greater number of teeth (Binney says 

 about 28-1-28), and perhaps in the very definite ribbing of the jaw. 

 I call it variety a, so that it can be referred to separately, but it does 

 not seem wise to give it a name. P. auratus (Tate), from Nica- 

 ragua, may perhaps be a form of the same species. On the other 

 hand the Mexican P. saltei (Cr. & Fisch.) and P. crosseana (Strebel) 

 appear to belong to the group of typical Philomycus. 



On his way home, Mr. Bethel collected a couple of Philomycus at 

 New Orleans. These are P. caroliniensis (Bosc.) of the form which 

 I separated (Ann. Mag. Nat. Hist., Nov., 1890, p. 382) as nebulosus. 

 This is the common, widely distributed animal, from Canada south- 

 ward ; current opinion does not support my attempt to separate the 

 true P. caroliniensis from Virginia, but I am not yet altogether sat- 

 isfied that careful study will not confirm the supposed distinctions. 



