No. I.] STUDIES ON LIMULUS. 3 



over a part of it in the form of some rough sketches and notes 

 to Mr. Reclenbaugh, then a student in the biological laboratory 

 at Dartmouth. Mr. Redenbaugh began the work anew, and 

 with great care and skill has brought it to completion. His 

 work on the endosternite of Lhmdus coincides very closely 

 with my own. The drawings that accompany this paper have 

 been made along the lines of my original sketches, some of 

 which were intended to emphasize the relations of the cranial 

 cartilages to the nervous system, and to show their resem- 

 blance to the corresponding parts in vertebrates. But every 

 drawing has been made from the dissections, and with the 

 utmost fidelity to details of size and position. 



The descriptions of the endosternite of Apits and Mygale, 

 with some unimportant exceptions, are the work of Mr. 

 Redenbaugh. 



Another paper, belonging to this series, on " The Structure 

 and Development of the Nephridia, Branchial Cartilages, and 

 Genital Ducts of Limulus," by Miss Hazen and myself, is 

 completed and in the hands of the publishers, and further 

 work on the histology and development of the endosternite 

 and branchial cartilages is in progress. 



The second paper of this series, that on " The Peripheral 

 Nervous System of Limulus," was begun so"me years ago, and 

 considerable progress was made on it. But the work was 

 laid aside for a time, owing to the pressure of other duties ; 

 the notes and drawings were finally given to Mr. Redenbaugh, 

 who went over the entire subject again, receiving from 

 Dartmouth College, in recognition of his work, the degree 

 of Ph.D. 



A description of the " Structure and Development of the 

 Central Nervous System of Limulus " is being prepared, also 

 papers on the "Physiology of the Brain and Spinal Cord." 



W. Patten. 



The structure, which has been called by various names, viz., 

 prosomatic endochondrite, or endosternite, cartilaginous ster- 

 num, endocranium, and plastron, has been found in many of 

 the Arachnida and in a few Crustacea. In all cases it is a 



