410 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



of the typical genus. The name Anceidce should perhaps be restored in 

 case Risso's species should not prove to be congeneric with Gnathia 

 termitoides Leach, Cancer maxillaris Montagu.* 



Gnathia Leach. 



GnatMa Leach, Ed. Encyc., vol. vii, p. "402" (Am. ed., p. 240), "1813-14." 



Praniza Leach, MSS. 



Anceus Risso. Crust, de Nice, p. 51, 1816. 



Head very large and quadrate in the male, smaller and subtriangular 

 in the female; first pair of legs operculiform in the male, subpediform 

 in the female; pleon much narrower than the thoracic segments, with 

 nearly parallel sides, and a sharply triangular telson. 



The name Anceus Risso, which has been used by modern writers for 

 this genus, ought, according to all rules of priority, to give way to 

 Gnathia Leach, as acknowledged by Bate and Westwood,t who, however, 

 hesitated to restore the name on account of Kirby's coleopterous genus 

 Gnathium. While the undoubted priority of the name is a sufficient 

 reason for its re-establishment, it may be worth while to add that 

 Gnathia was not restricted by Dr. Leach to either sex alone, as that 

 author had the sagacity to "suspect that Oniscus coeruleatus Montagu 

 [Praniza coeruleata Desin.] was the female" of Gnathia, and, as far as I 

 am aware, did not publish a generic name for the Praniza-form, although 

 the name Praniza was used by him as a manuscript name, and as such 

 appears to have been published by Latreille in the Encyclopedic 

 M^thodique, which I have not been able to consult. 



Gnathia cerina Harger (Stimpson). 



Praniza cerina Stimpson. Mar. Inv. G. Manan, p. 42, pi. iii, fig. 31, 1853. 

 Packard, Mem. Bost. Soc. Nat. Hist., vol. i, p. 296, 1867. 

 Verrill, Am. Jour Sci., Ill, vol. vi, p. 439, 1873; vol. vii, pp. 38, 41, 411, 



502, 1874; Proc. Am. Assoc., 1873, pp. 350, 354, 358, 362, 1874. 

 Anceus americanus, Stimpson, Mar. Inv. G. Manan, p. 42, 1853. 

 Gnathia cmna Harger, Proc. U. S. Nat. Mus., 1879, vol. ii, p. 162, 1879. 



PLATE XII, FIGS. 75-79. 



It will be convenient first to describe the male of this species and then 

 the female and larval forms. The powerful and prominent jaws in front 

 of the large quadrate head of the males of this small Isopod serve to 

 distinguish it from any other on our coast. 



The shape of the body is well described by Dr. Stimpson, as " regu- 

 larly rectangular, abruptly narrowed at the commencement of the abdo- 

 men, which has the appearance of another very small rectangle set into 

 the first, and of only one-third its width." It is somewhat bristly hairy, 

 and much tuberculated and roughened above, especially on the lateral 

 portions of the head and on the anterior thoracic segments. The head 

 is broader than long, depressed medially in front and produced into a 

 rounded lobe between the projecting upturned jaws. The eyes are small 



* Trans. Linn. Soc., vol. vii, p. 65, pi. vi, fig. 2, 1804. 

 tBrit. Seas. Crust., voL ii, p. 169. 



