24 NATURAL SCIENGE. 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 ‘‘Encyclopedia 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 
Euplectella aspergillum, Owen, appeared in 1841; and in 1857 a new 
species of the same interesting genus was described. ‘‘The threads 
of the Euplectella 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 pavi 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 Tvichina 
spivalis, 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 Protichuites, 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.”’ 
