182 
MOLLUSCOIDA. 
Diplosomid^. 
Fseudodidemnum, g.n. No endostylal appendage j branchial opening six- 
toothed, P, crystallimim^ sp, n., Giavd, 1. c. p. G56, Roscolf. 
Astelliumj g. n. No endostylal appendage ] branchial opening without 
teeth. A. spongiforme, sp. n., id. ibid. p. 657, pi. 23. fig. 1, and pi. 26. figs. 6 & 7, 
Roscofi*. 
Pyrosomidas. 
P. Pave SI thus sums up the results of his researches into the 
circulation of Pyrosoma giganteum : — 1. The circulation is of the 
alternating type, whether in adults, embryos, or nurse (cyatho- 
zoid). 2. In the adults it is lacunar and independent, in the 
embryos vascular and common to the young colony. 3. The 
heart of the evanescent nurse presides over the circulation of the 
compound embryos, which is carried on by means of a double 
cord, derived from the development of a canal ; and the vascular 
circle is closed in the nurse and in the last of the embryos. 
4. The heart of the nurse is replaced by the hearts of the em- 
bryos, coexisting with the former for a certain time, but inde- 
pendent of it. 5. The circulation in the embryos, produced by 
budding, takes place as in the compound embryos, but is depen- 
dent on the mother in place of the nurse. 6. A lacunar circu- 
latory system commences at the time that the vascular system 
begins to atrophy. 7. The pulsations of the heart are of variable 
duration. Q. J. Micr. Soc. (2) xii. pp. 275 & 283, pi. 12. 
Salpid^e. 
Salpa herculea and cymbiola, spp. nn., Dali, Am. J. Conch, vii. pp. 158 & 
169, North Pacific, near the Aleutian Islands. Length of the first 8 inches; 
only the solitary form of both known. 
Appendiculariid^. 
H. Pol, in an anatomical description of the family generally, 
points out the formation of the branchial openings by a double in- 
vagination, outside of the skin and inside of the pharynx, these 
meeting and resulting in a perforation fringed with vibratory cilia. 
He describes the endostyle as a canal for the secretion of slime, 
which is divided by the currents within the pharynx into several 
threads, directing the nutritive particles contained in the water 
to the oesophagus. He also describes the heart and the lacunar 
course of the blood, the ganglia and nerves, the testicle and ovary, 
situated (with one exception) one near the other in the same in- 
dividual. The latter evacuates its contents by bursting ; and the 
animal dies soon afterwards. Mem. Soc. Phys. Genev. xxi. pt. 2, 
pp. 445-498, with 11 plates. 
