22 CHILOPODA. 
millim.), of a much more uniform green tint, with shorter and stouter anal legs. The 
largest I have seen, a specimen from Omilteme, measures, however, 86 millim. 
The specimen of which a coloured figure is given on Tab. II. fig. 2 is from San 
Andres Tuxtla. It and another were acquired by the British Museum in 1861, and 
according to a note in the register they were identified by de Saussure himself as 
S. tolteca. ‘They are said, moreover, to be the types of this species. This, however, 
they clearly are not; for the types of S. tolteca came from Cuautla, Vera Cruz, and are 
said to vary in length from 80-85 millim., whereas the San Andres specimens are 70 
and 75 millim. respectively. The smaller one is like the larger, except that the anal 
legs are thinner and the spinous process on the femur longer. This fact is interesting, 
inasmuch as the great length of this spinous process is one of the first characters to 
strike the eye as distinguishing de Saussure’s figures of S. azteca and S. otomita, not 
to mention 8. maya from 8S. tolteca. In fact, an examination of the available material 
seems to me to show that the structure of the anal somite, which usually furnishes trust- 
worthy characters, cannot be safely used as a criterion for distinguishing the so-called 
species enumerated in the above synonymy. For instance, the pleural process may be 
longish or quite short, so also may the spinous process on the femur, and the anal legs 
may be stout and short or longer and thinner. I believe, in fact, that these organs 
vary considerably with sex and age. On Tab. II. figs. 2c-2hI have depicted the 
anal somite of three specimens of a Scolopendra selected from a large series that was 
obtained some years back at San Diego, Texas, by Mr. William Taylor. ‘These figures, 
drawn to the same scale, well illustrate the variations that have just been mentioned. 
I may add, moreover, that other specimens from the same set further illustrate the 
same truth, scarcely any two of them being alike. ‘These Texan specimens I cannot 
distinguish from the Central-American forms named S. azteca, S. tolteca, &c.; and, 
so far as I can ascertain, they are nothing but S. viridis of Say, which was described 
from Florida, and, according to Bollman, is spread over the South-eastern States of 
the Union as far to the north as Tennessee. The last-named author, moreover, 
distinguishes between S. viridis, which is found to the east of the Rocky Mountains, 
and S. pachypus of Kohlrausch, which occurs in California. I have not, unfortunately, 
seen specimens from California that are at all like S. viridis; but the thickness of 
the anal legs in S. pachypus, upon which Bollman relies, is, it appears to me, an 
untrustworthy character. 
The arguments which thus lead me to consider that the Mexican species are to be 
called S. viridis of Say are founded upon the assumption that Wood and Bollman are 
correct in their identification of S. vivzdis. It must be remembered, however, that the 
species in question is based upon specimens presenting a most unusual type of coloration 
—that is, in having a green band down the back. ‘This at least appears to me to be 
the case from reading Say’s description, where he says the posterior segments are 
margined with yellow. Wood seems to me to have wrongly interpreted this statement, 
