ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
539 
pleura, Phoronis ) be present with chordoid walls. Ventral sucker form- 
ing the organ of attachment throughout life. 
(1) Ceplialodiscida. Protomere persistent throughout life as adhesive 
organ. Twelve pinnate plumes with eyes. Notochords and chordoid 
gill-slits persistent. Ventral sucker forms budding organ. Habitat, 
creeping, sedentary, and coenoecial. 
(2) Phoronida. Loss of protomere, atrial grooves, subneural gland, 
and notochords in adult. Great development of lophophoral tentacles 
(unbranched) and of chondroid tissue. Paired nephridial apertures in 
metameres. Metamere elongated, with circular and longitudinal muscles 
(as in Balanoglossus). Permanent fixation by ventral sucker. Habitat 
sedentary and tubicolous. 
(3) Rhabdopleurida. Protomere persistent. No notochord (?) nor 
pharyngeal clefts (?) in adult. Two pinnate plumes. Attached by 
hypertrophied ventral sucker. Habitat creeping, tubicolous. 
New or Rare British Marine Polyzoa.* — Mr. S. F. Harmer has 
notes on Hypopliorella expansa Ehlers from the tubes of Chsetopterus ; 
Escharoides quincuncialis Norman, dredged off Plymouth ; Micropora 
complanata Norman, common on the shore-rocks of the Scilly Isles ; and 
Schizoporella cristata Hincks on a scallop-shell dredged off Plymouth. 
Echinoderma. 
New Echinothurid.j — Hr. R. Koehler describes Sperosoma Grimaldii 
as type of a new genus of Echinothuridae. Several specimens of large 
size (22 cm. in diameter) were obtained by the 4 Hirondelle ’ and 
4 Princess Alice * off the Azores. The generic characteristics are as 
follow : — The ambulacral zones of the ventral surface are considerably 
enlarged by the exaggerated development of the poriferous plates, which 
attain a size approaching that of the principal ambulacral plates. The 
latter form, in each ambulacral zone, two median rows accompanied on 
each side by three distinct rows of poriferous plates, of which each bears 
a pair of pores. The interambulacral zones of the ventral surface are, on 
the contrary, restricted in size, at least in the proximal half. On the 
dorsal surface the ambulacral and interambulacral zones have the same 
dimensions and triangular form ; the aquiferous pores form a single 
regular row in the middle of each ambulacral area. The test is very 
flexible, and the general cavity does not contain the vertical muscles 
which form partitions in Asthenosoma. Koehler also notes that he has 
recognised Stewart’s organs in the above form and in Phormosoma 
atlanticum and Asthenosoma hystrix. As Jeffrey Bell has pointed out, 
Stewart’s organs are absent in other species of Phormosoma. An intestinal 
siphon, which seems to have escaped attention, is present in four species. 
Abnormalities in Echinoid Ova after Fertilisation.:): — Prof. S. L. 
Schenk has studied artificially fertilised ova of Toxopneustes and Echinus 
with reference to abnormalities in early stages of development. He 
describes in particular the divergent phenomena exhibited by ova which 
have not attained complete maturation, whose nucleus, in other words, is 
* Journ. Mar. Biol. Ass., v. (1897) pp. 51-3. 
t Zool. Anzeig., xx. (1897) pp. 302-7 (1 fig.). 
X SB. K. Akad. Wiss. Wien, cv. (1896) pp. 168-85 (4 figs.). * 
