TILE MYRIAl'ODA OF NORTH AMERICA. 



215 



very readily to the preceding species, but it seems to me to tit this one rather more 

 closely, and as the choice must be somewhat arbitrarily made in the absence of psoof as to 

 which he intended, I think the name should be allowed to rest here. Length, i inch. . 



Sab. Pennsylvania.— II. 0. Wood, Jr., M.D. Michigan.— Prof. Miles. Canada.— Pro!'. Dawson. 



Fi K . 42. 



P. SERRATUS. 



P. saturate brunneus; antennis pubesoentibus, olavatis; scutis, singulo squamarum Beriebus duabus et altera, 

 obsoleta ornato, marginibus lateralibus serratis j appendicibus masculis pilosis, spina terminate duplioa. (Fig. 42.) 



Deep brown ; antennas pubescent, clavatc ; scuta each with two rows of squama and a third obsolete scries, their 

 lateral margins serrate; male appendages pilose, their terminal spine double. 



I'. SERRATUS, Say, Journ. Acad. Nat. Sci., 1st series, vol. ii, p. 106. 



" Gervais, Suit, a Buffon, Apteres, vol. iv, p. 105; Exped. L'Amer. du Sud (Castelneau), Myriap., 



p. 6. 



" Newport, Cat. Brit. Mus. ? 



The pilose anterior aspect of the head is quite broad and triangular, with the vertex 

 furrows strongly pronounced. The first scutum is transversely oval, 

 with three rows of elevated, obtuse, minute scales. On most of the 

 other scuta there arc two serigs of similar larger scales, with an obso- 

 lete scries of very broad ones in front of them. The posterior row is 

 generally composed of six, the next of four. The lateral lamina are 

 large, and have their margins much more serrulate than in P. Cana- 

 densis. The Last scutum is triangular and decurvate. The prominent 

 knob-like portion of the male appendages is very hairy. The terminal 

 spine is double, one portion being much more robust than the other, blunt and nearly 

 straight. The longer piece is distally very slender and bent over the other. 



Length I of an inch. 



It will be stum, on comparison of my description with the original one of Mr. Say, 

 that it differs somewhat. The fact of Say's not mentioning the existence of the obsolete 

 series of scales on the anterior surface of the scuta, lias been the cause of M. Saussure's 

 error. After carefully going over the whole ground, there is but little doubt in my 

 mind that this is the species meant to be indicated by Say. If not, it is an undescribed 

 species, and the real P. serratus has not yet come to light. It is an unfortunate fact 

 that the earlier descriptions of Myriapoda arc by no means exact, the authorities not 

 appearing to have had any definite idea as to what constituted specific characters. If 

 we interpret their records too closely, we may be led to false deductions. 



Ilab. Pennsylvania, &o. 



