460 



1837. Tetkagnatha obtusa C. Koch, Uebers. d. Arachn. -Syst., 1, p. 5. 

 91837. „ gibba id., ibid. 



91847. „ gibbosa Walck., Sur une nouv. fatn. du genre Te- 



tragn. , in Ann. de la Soc. Ent. de France , 

 2 Ser., V, Bull., p. lxiv. 

 1861. „ OBTUSA Westr., Aran. Suec, p. 86. 



1866. „ „ Mkkge, Preuss. Spinn., I, p. 39, PI. 15, tab. 27. 



1870. „ Extensa Thor., Eem. on Syn., p. 40 (ad part.). 



1870. „ obtusa L. Koch, Beitr. z. Kenntn. d. Arachn. -fauna 



Galiz. , p. 16. 



91872. „ GR03NLANDICA Thor., Om nagra Arachn. fr. Gronl., in 



Vet.-Akad. Forhandl., XXIX (1872), p. 151. 



I have already, pp. 41 and 42, expressed my opinion, that T. 

 obtusa C. Koch could not he considered as a different species from 

 T. extensa, at least not on the strength of the characteristics appealed 

 to by C. Koch, Westking and Menge. Since that time L. Koch, 

 in his work "Beitrage z. Kenntn. d. Arachn. -fauna Galiz.", has not 

 only taken up T. obtusa as an independent species, but has from 

 "2\ externa" separated two more species, "2\ NoHickii" and n T. pini- 

 cola". These three forms differ, it is true, from each other in cha- 

 racteristics quite as good as those which distinguish T. obtusa; and 

 if there were no transition-forms between them, I should be much 

 more inclined to acknowledge the independence of all four forms 

 than to separate T. obtusa only as a species distinct from T. ex- 

 terna, if the other three forms are to be included under that name. 

 (I united above, 1. c, all four forms in question under the name T. 

 externa). T. pinicola appears to be the most distinct of these forms, 

 and is perhaps a good species; but the other three are certainly 

 nothing more than varieties of one and the same species, or perhaps 

 rather "incipient species". — I cannot, I believe, do better than give 

 in Dr L. Koch's own words the characteristics whereby one can 

 most readily distinguish full-grown individuals of the forms be- 

 fore us. 



"In T. externa the sternum is brownish yellow with a slight 

 shade of black; the lateral eyes are situated nearer together than are 

 the centre eyes: in the female the claw of the mandible has near 

 the base a little tooth, in the male there appears in front of the 

 great spine on the upper side a little protuberance. Tetragnatha 

 Noioiehii has the sternum black with a triangular yellow spot at 

 the base: the lateral eyes of the two rows are as distant from 

 each other as are the centre eyes, the claw of the mandibles in 



