286 Ortmcmn — Crangopsis vermiformis. 



mediate between the Arthrostraca and Thoracostraca : but in 

 pointing to the resemblance to the Amphipods they were 

 wrong, since there are no closer relations present to that order. 

 The other genera referred by Brocchi to the JVectotelsoniäce are 

 only incompletely known, but their general appearance strongly 

 favors the opinion that they really belong to the relatives of 

 Uronectes. The description of the genus Nectotelson of the 

 Permian of Autun, France, is very poor and contradictory. 

 Brocchi gives it seven thoracic segments (p. 6) and four abdom- 

 inal segments, but his figures show nothing that might warrant 

 this number, and fig. 1 (pi. 1), indeed, shows clearly that the 

 number four for the abdominal segments is incorrect. Further, 

 he says (p. 7) that probably the eyes were small and sessile : 

 but the specimens did not show any traces of these organs ! 

 He did not discover in his specimens an appendage of the 

 antennae: these characters and the much smaller size are the 

 only differences of Nectotelson and Uronectes. The limbs of 

 Nectotelson (pi. 1, ß.^. 2) are badly preserved, but they resemble 

 apparently those of Uronectes.* 



As regards the genera JPalceocaris and Acanthotelson of 

 Meek and Worthen,f I refer only to the descriptions and resto- 

 rations given by Packard;): from which it is apparent that both 

 are closely related to Uronectes. 



In order to get an approximate idea of the systematic posi- 

 tion of Brocchi's JYectotelso?iido3, we may rely upon a combi- 

 nation of the characters of these three or four genera, and if 

 we consider these characters as conclusive for this family, we 

 may say that the Nectotelsonidoe show the typical characters of 

 the subclassis Malacostraca ; but further on they unite charac- 

 ters of the Arthrostraca (the missing carapace) with those of 

 the Thoracostraca (stalked eyes), thus proving to be a primitive 

 group from which the former as well as the latter might be 

 derived. 



I may add here that Packard creates the suborder Sy near ida 

 for these genera, § which thus consists of Brocchi's family 

 Nectotelsonidm. 



* It is astonishing that Brocchi in comparing Nectotelson with Uronectes did not 

 consult the paper of Jordan and Meyer quoted above, and that he describes a 

 very bad figure that we possess of Gampsonyx (he gives a copy pi. 1, fig. 7), while 

 Gampsonyx (Uronectes) is known as completely as we might expect to know a 

 Palaeozoic Crustacean. 



f Palceocaris typus, Coal Measures of Illinois (Proc. Acad. Philad., 1865, p. 49, 

 and Geol. Surv. 111., ii, 1866, p. 405; iii, 1868, p. 552). Acanthocaris, three 

 species from the Coal Measures of Illinois (ibid.). A second species of Palceocaris 

 has been described by Woodward from the Coal Measures of England (Geol. 

 Magaz., 1881, p. 533). 



X Mem. Nat. Acad. Sei., Washington, iii, 1886, aud Proc. Boston Soc. N. H., 

 xxiv, 1889. 



§ Compare Caiman, 1896, p. 801, footnote 1. 



