THE CULT OF THE TRILOBITES 603 



C. E. Beecher of Harvard set to work. He brushed or abraded 

 away the shale from the hard minerahsed fossils, which are 

 only about an inch in length. He drew carefully the minute 

 structure revealed, and, in a series of papers from 1893 to 1902 

 made known the appendages of trilobites almost as if the animals 

 were alive. 



Beecher's sudden death in 1904, while making a drawing 

 of Cryptolithus, left to his pupil and successor P. E. Raymond 

 the task of bringing together the latest results of his research, 

 Raymond has now published much of the evidence for the first 

 time, by means of a remarkable series of photographs, and by 

 reconstructions made under his care by Elvira Wood. His 

 descriptions lead up to a consideration of the origin and affini- 

 ties of trilobites, which gives much room for thought, and, as 

 the author will be the first to admit, much also for differences 

 of view. 



The appendages of trilobites include tactile organs, the 

 antennules, which are almost straight in Ceraurus, delicately 

 waved, yet perhaps rigid, in Triarthrus, and bent backwards 

 in typical specimens of Cryptolithus. The other appendages, 

 two to each body-segment, balancing one another on opposite 

 sides of the axis, with others on the head-shield and pygidium, 

 are of simple and almost uniform character. The type is 

 " biramous," a jointed limb used for crawling and swimming 

 having behind it — that is, inwards from the under surface of 

 the animal^ — a limb bearing feathery rodlets or hairs ; it seems 

 certain that this inner limb was concerned with respiration. 

 The five pairs of appendages attached behind the antennules 

 on the head-shield have their inner ends notched for masticating 

 food. 



Raymond lays less stress than his predecessors on the 

 browsing habits of trilobites, and gives them more credit for 

 swimming than has hitherto been allowed. For him, the 

 ancestor was a swimming arthropod of few segments. On the 

 adoption of a crawling habit, an unsegmented shield was needed 

 for protection of the upper surface of the animal. The increase 

 in number of the appendages led to a breaking up of the cara- 

 pace as activity developed, and the many-segmented forms, 

 though existing as far back as the Cambrian period, have ac- 

 quired a secondary character. It will be seen how widely this 

 suggestion differs from that previously entertained. More 

 important, perhaps, is the detailed comparison of trilobites 

 with the modern phyllopods Branchipus and Apus, and 

 the conclusion that these lie on a separate line, that they 

 are less primitive than the trilobites, and that the latter 

 represent the stock from which all other Crustacea have 

 diverged. 



