Mr. MacLeay on some new forms q/^Arachnida. 7 



bark in search of insects. The difference between the West 

 Indian subgenera Aissus and Hypoplatea is that in the former 

 the first pair of feet are the longest, whereas in Hypoplatea it 

 is the penultimate pair; besides in Aissus the two large lateral 

 ocelli are round; in Hypoplatea they are oval. The mentum 

 of Omalosoma, another subgenus of Selenops, is not truly se- 

 micircular, nor does that kind of spider lie so broad and flat 

 on the ground as Hypoplatea. In general aspect Hypoplatea 

 bears great resemblance to the genus Artamus of Koch, but 

 differs from it altogether in the disposition of the eyes. Tha- 

 natus, Koch, Artamus, Koch, Selenops, Duf., Philodromus, 

 Koch; and Olios of Walckenaer (which last is identical with 

 Koch's Ocypete, a name that cannot stand as it has been else- 

 where employed), all form a group of laterigrade spiders which 

 perhaps are the swiftest of the whole order. They lie in wait 

 for their prey like the saltigrade spiders and those other late- 

 rigrade spiders of which Thomisus is the type ; but instead of 

 leaping on their food like Thomisus, they catch it by their ex- 

 treme velocity in running. They differ thus also from the Ly- 

 cosina, which regularly hunt down their prey*; and I may take 

 this opportunity of observing that Koch makes a gross mis- 

 take in placing Walckenaer's genus Ctenus among the Krab- 

 benspinnen. Ctenus is not a laterigrade spider, but has all the 

 habits and structure of the Wolfspinnen, as I know by per- 

 sonal experience, the genus being very common in Cuba. 

 Latreille is also wrong in calling the Wolfspinnen a citigrades" 

 par excellence, for they are far less swift than the present 

 group. 



I have introduced Hypoplatea in this place, not so much 

 from the form being new to science, as in order to show the 

 proper mode of considering the ocellar system of spiders 

 when we are investigating their affinities. Thanatus and Ar- 

 tamus have nearly the typical system of ocelli which prevails 

 throughout the greatest part of the laterigrade spiders, of 

 which it may be said that the arch of their eyes is typically 

 convex outwards in opposition to that of the Drassina, where 



* On this account Walckenaer is wrong in placing the genus Oxyopes, Lat, 

 or his own Sphasus among the Lycosina. I have always found these Oxyopes 

 on syngenesious flowers sedentary like Thomisi. One large green species of 

 Oxyopes is common in Cuba. I call it O.floricola. 



