HISTORICAL REVIEW. I 9 



Castelnau (1843) described and figured a Phacops said to come from Cacapon Springs, 

 West Virginia, which he thought possessed remains of appendages. There is nothing in the 

 description or figures to indicate exactly what was present, but it is very unlikely that any 

 limbs were preserved. The broad thin "appendage" figured may have been a fragment of 

 a thoracic segment. This specimen was evidently described by Castelnau before 1843, as 

 is inferred from a reference in the Neues Jahrbuch, 1843, P- 54> but I have not seen the 

 earlier publication. 



Burmeister (1843-1846), in his "Organization of the Trilobites," reviewed in cxtenso 

 the history of the search for appendages, and concluded that they must have been so soft 

 as to preclude the possibility of their being preserved as fossils. "Their very absence in 

 fossils most distinctly proves their former real structure" (p. 10). In figures 7 and 8 on 

 plate 6 he gave a restoration of the ventral surface of an Asaphus, the first restoration of 

 the ventral anatomy to be attempted. Since he chose modern branchiopods as his model, 

 he did not go so far wrong as he might have done. Still, there is little in the figure that 

 would now be accepted as correct. The following quotation will serve to give the opinion 

 of this zoologist, who from his knowledge of the Crustacea, was the most competent of the 

 men of his time to undertake a restoration of the appendages of the trilobites: 



. . . in giving a certain form to the feet in the restored figure, I have done so rather intending to 

 indicate what they might have resembled, than with any idea of assuming their actual form. I merely assert 

 that these organs were soft, membranous, and fringed, adapted for locomotion in water, placed on the 

 abdominal portion of the body, and extending sidewise beneath the lateral lobes of the rings, as shown in 

 the ideal transverse section. These feet were also indented, and thus divided into several lobes at the open 

 lower side, and each separate lobe was furnished at the margin with small bristles serving as fins. The last 

 and external lobe was probably longer, smaller, and more movable, and reached to the termination of the 

 projecting shell lobe, bearing a bladder-shaped gill on the inner side (1846, p. 45). 



McCoy (1846) observed in several trilobites a pair of pores situated in the dorsal fur- 

 rows near the anterior end of the glabella. He showed that the pits occupy precisely the 

 position of the antennae of insects and suggested that they indicated the former presence 

 of antennae in these trilobites (chiefly Anipyx and "Trinucleus"). The evidence from Cryp- 

 tolithus, set forth on a later page, indicates the correctness of McCoy's view. 



Richter (1848, p. 20, pi. 2, fig. 32) described and figured what he took to be a phyl- 

 lopod-like appendage found in a section through a Phacops. Without the specimen it is 

 impossible to say just what the structure really was. The outline figure is so obviously 

 modeled on an appendage of Apus that one is inclined to think it somewhat diagrammatic. 

 In calling attention to this neglected "find," Clarke (1888, p. 254, fig.) interprets the 

 appendage as similar to the spiral branchiae of Calymcne senaria, and adds that he himself 

 has seen evidence of spiral branchiae in the American Phacops rana. 



Beyrich (1846) described a cast of the intestine of "Trinucleus," and Barrande (1852) 

 further elaborated on this discovery. 



Corda (1847) made a number of claims for appendages, but all were shown by Bar- 

 rande (1852) to be erroneous. 



Barrande (1852, 1872) gave a somewhat incomplete summary of the various attempts 

 to describe the appendages of trilobites, concluding that none showed any evidence of other 

 than soft appendages, until Billings' discovery of 1870. 



Volborth (1863) described a long chambered tubular organ in Illccnus which be believed 

 to represent a cast of the heart of a trilobite, but which has since been likened by writers to 

 the intestinal tract in "Trinucleus." 



