Glyptoci'inus Shaffen. 277 



character, by which, all Cirripedia may be distinguished from other 

 Crustacea ; this character is, that they are attached to some foreign 

 object, by a tissue or secretion (for at present I hardly know which to 

 call it), which debouches, in the first instance, through the prehensile 

 anteuuse of the larva, the antennae being thus embedded and pre- 

 served, in the center of the basis. The cementing substance is brought 

 to its point of debouchement, by a duct, leading from a gland, which 

 (and this is perhaps the most remarkable point in the natural history 

 of the class) is part of and continuous with the branching ovaria. 

 When we look at a Cirripede, we, in fact, see only a Crustacean, with 

 the first three segments of its head much developed and enclosing the 

 rest of the body, and with the anterior end of this metamorphosed 

 head fixed by a most peculiar substance, homologically connected with 

 the generative system to a rock or other surface of attachment." 



It will appear that the character, upon which the Cirripedia are 

 distinguished, from other Crustacea, is not only wanting, in our 

 specimen, but it will require some ingenuity to construct the animal 

 and supply this character. The two series of valves or plates do not 

 overlap, as they do in Scqlpellum ornatum, or in Loricida piilcheUa and 

 other species described by Mr. Darwin. Indeed, about the only 

 resemblance, between our specimen and any well determined Cirripede, 

 is to be found in the surface ornamentation, which is of very slight 

 importance, in determining its affinity. It is not therefore too much to 

 say, that we are by no means certain, that we have here, under con- 

 sideration, a fossil Cirripede, and that it may be possible, that we have 

 the long sought for appendage to Billing's trilolnte. Against the 

 latter view, in addition to the fact, that nearly all naturalists think it 

 quite improbable that a trilobite had any such appendage, it may be 

 urged, that the plates are not tuberculated as all trilobites are, but 

 transversely lined, in -a way, essentially difierent, from the markings 

 on any known part of a trilobite ; moreover, it is difficult to see how 

 such legs could be disposed of wdien the animal curled up, and why it 

 is that the plates are not specially abundant, among the remains of 

 trilobites, instead of being somewhat uniformly scattered through the 

 rocks, without regard to the quantity of fragments or well preserved 

 trilobites, where they most abound. 



Ghjjjfoerinus 'Slmfferi. (S. A. INIiller). 



Body very small, only a little larger than the column, and Avithout 

 sculpture or other ornamentation. Basal pieces small, pentagonal; 

 radial j)ieces small and wider than long. The third radials sujiport, 



