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- 5°4> but I have not seen the 
earlier publication. 
Burmeister (1843-1846), in his "Organization of the Trilobites," reviewed in extenso 
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 antennas of insects and suggested that they indicated the former presence 
of antennas in these trilobites (chiefly Ampyx and "Trinuclcus"). The evidence from Cryp- 
tolithuSj 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 Calymene senaria, and adds that he himself 
has seen evidence of spiral branchia; in the American Phacops rana. 
Beyrich (1846) described a cast of the intestine of "Trinuclcus," 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 llhcnus 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 "Trinuclcus." 
