1888.] NATURAL SCIENCES OF PHILADELPHIA. 429 



moral as to "the uncertainty of ofF-hand identifications of these draw- 

 ings by two persons both familiar with the common spiders of the 

 Z^orthern States." But the inference is wholly deceptive, for the 

 basis of his comparison is entirely faulty and unfair. He published 

 a list of thirteen (13) numbers, noted by him as identified thirteen 

 years ago when he visited the British Museum. Of these, four 

 numbers are of other species than Orbweavers ; two other 

 numbers are Orbweavers which I did not notice or did not list. 

 Emerton includes all these in his estimate; but it is manifest that 

 any comparison, in order to yield just results, should throw out these 

 six numbers not listed or considered by me, and should be con- 

 fined wholly to the seven numbers which both of us attempted 

 to identify. Such a comparison justifies a conclusion quite the 

 reverse of Mr. Emerton's. We agree as to the following: Nos. 121, 

 116, 117, 79 and 80 — five out of the seven. How stands it as to the 

 remaining two numbers, (one species) 77 and 78? Mr. Emerton 

 marks them with a generic name, " Uloborus." I list them as 

 *' Cyrtophora caudata Hentz, " but in a secondary place, and in a 

 foot-note express my uncertainty as to the identification, and think 

 they may prove to be my own species C. bifurca. Concerning the 

 only species, (embraced in these two numbers) about which we differ, 

 I express my uncertainty, and Emerton merely gives a generic name, 

 showing his uncertainty as to the species. In other words, we are 

 both more or less uncertain, and thus we agree in that respect also. 

 I submit, therefore, that instead pf justifying Mr. Emerton's inference 

 of uncertainty, and thus casting cloubt upon my identifications, the 

 contrary is shown, for we actually agree in one way or another on 

 every number concerning which both give an opinion. In other 

 words, we absolutely agree concerning five-sevenths of the numbers 

 mutually identified, and agree to be uncertain concerning the other 

 two-sevenths. 



As to which list is nearer the truth in the one uncertain fiictor, 

 I do not venture to decide. Turning to the original description of 

 Walckenaer,^ one finds that he is left in doubt, and the doubt can per- 

 ha})s not be removed. Walckenaer makes one of the numbers a variety 

 of the other. If we read the description of the animal itself, INIr. 

 Emerton's identification as Uloborus is well justified; but when we 

 turn to Abbot's account of the habits of the spider, we find that 

 they differ entirely from all we know of Uloborus, and correspond 

 exactly with the peculiar habits of Cyclosa caudata, especially the 

 habit of covering the central diameter of its vertical net with pellets 

 of silk mixed with insect detritus. Uloborus spins a horizontal 

 snare; has many ribboned decorations as caudata frequently has, 

 but never has been observed, so far as I know, to decorate her orb 

 with insect scalpage. 



1 Op. cit., p. 144. 



