432 PROFESSOR E. RAT LANKESTER. 



or from Naples. If any naturalist reading these lines should 

 be able and willing to furnish me with specimens he would 

 confer a great favour on me by communicating with me. 



The question in regard to Lernanthropus may be further 

 stated in this way : is the tubular vascular system of that 

 animal an heirloom from Annelid-like ancestors with the cha- 

 racteristic Chsetopod^s vascular system ? or is it a special de- 

 velopment de novo peculiar to this Copepod ? 



One of the most attractive features about the theory of 

 dilated veins in the Arthropods is the simple explanation which 

 it affords of an otherwise puzzling structure, namely, the 

 Arthropod heart. I therefore venture to present here a dia- 

 gram which I have made use of during the last six years in my 

 lectures illustrating the possible — I think we may say the 

 probable — steps by which the Arthropod heart, with its curious 

 valvate ostia and blood-holding pericardial space, was developed 

 from the dorsal vessel of a closed " tubular" vascular system 

 such as that of the earthworm. 



