24 NATURAL SCIENCE. Jan.. 



were described ; in Lectures on the Comparative Anatomy of the 

 Invertebrata, largely based on discourses delivered during his occu- 

 pancy of the " Hunterian Chair," in that great institution, the foster- 

 parent of so many distinguished reputations ; in an article on 

 Cephalopoda contributed to the "Encyclopaedia of Anatomy and 

 Physiology," and in that on the Mollusca, including the Molluscoidea, 

 to the eighth edition of the " Encyclopedia Britannica." A remark- 

 able article, entitled '• Palaeontology " was first published in the latter 

 work, and subsequently enlarged and re-issued as a " Systematic 

 Summary of Extinct Animals and their Geological Relations " in 

 1861 as a separate publication. (Part I., relating to Invertebrata.) 

 This is one of the best examples of Professor Owen's literary 

 powers of popular exposition of technical details. The Memoir on 

 " Parthenogenesis," treating of the phenomena of asexual generation 

 among certain groups of Invertebrates, belongs more properly to the 

 category of his speculative and philosophical inquiries. 



We will now refer briefly to some of the most important of Pro- 

 fessor Owen's publications on invertebrates, grouping them for con- 

 venience more in zoological order than chronological sequence. Ob- 

 servations on the structure of a new genus of " well-woven " sponge 

 Enplectella aspergillum, Owen, appeared in 1841 ; and in 1857 a new 

 species of the same interesting genus was described. "The threads 

 of the Eupleciella were not first spun and then interwoven," he wrote 

 in his second memoir on the genus, " but were formed as interwoven 

 the two processes going on simultaneously; or pari passu, in the living 

 state, the exquisite structure of the flinty framework may be veiled 

 by the delicate, gelatinous, enveloping, organic tissue." 



No less than five memoirs on the Entozoa appeared in the first 

 volume of the Transactions of the Zoological Society issued in 1836, 

 and his comprehension of " the structural differences existing among 

 them " induced him to propose a more natural classification of this 

 difficult group. His descriptions and figures of a new endo-parasite, 

 first discovered by Mr. (now Sir) James Paget, his fellow student, at 

 St. Bartholomew's Hospital, infesting the voluntary muscles of a 

 human subject, and the subsequent recognition by Zenkrer of Trichina 

 spiralis, Owen, as the cause of a troublesome and often fatal disease 

 now known as Trichinosis, led to results of practical utility to 

 mankind. 



An interesting paper, entitled Protichnites, was published in 1852, 

 wherein the fossil footprints of ancient crustaceans were tracked in 

 the sands of time. " Old Nature speaks as plainly as she can do by 

 these distinct symbols, and if we do not fully thereby read her mean- 

 ing, the fault is in our powers of interpretation. The creatures 

 which have left their impressions on the most ancient of known 

 sea shores belonged to an articulate and probably crustaceous 

 genus, and Limulus comes the nearest to my idea of the kind of 

 animal which has left the impressions on the Potsdam Sandstones." 



