PROFESSOR OWEN ON LIMULUS POLYPHEMUS. 209 



" The numerical correspondence of the lateral tributaries to the main median or sub- 

 median receptacles of the ova with the neural indications of the segmental constitution 

 of the two chief divisions of the body is less obvious than in those of the hepatic masses. 

 This may be due to the later period of development of the genital factories. 



" The part of the ramified ovarian system to which the term oviduct is here applied is 

 the tube, o, continued from the common stem of the three last-described tubes, and 

 passing backward, inward and downward, across the cephalo-thoracetral joint to the part 

 of the upper or inner surface of the ' opercular' limb, viii, shown in fig. 6, PI. XXXV. 

 The termination here of the oviduct {p) was rather prominent ; the outlet is transverse, 

 and formed by tumid labia, with the inner surface transversely plicate. 



" The bifurcation of the hind part of the ovary, before passing from the thoracetron 

 to the cephaletron, relates mechanically to the accommodation of the cardiac and intestinal 

 tubes during the frequent and forcible inflections of the two great body-chambers upon 

 each other. The laden ovarium, instead of being pressed down upon the heart (as it 

 would have been if it had been continued as a single median and vertically parallel 

 viscus across the joint where the cephaletron was depressed at an angle with the thora- 

 cetron), slips, by its division, on each side of the heart during the inflection. A similar 

 relation to convenience of package governs the forward extension of the ovarian biparti- 

 tion in relation to the main parts of the heart and intestine. 



" The most significant difference between the female organs of Limulus, and those of 

 the higher or malacostracous, squat-eyed Crustaceans is the absence of the dilated part 

 of the oviduct forming the copulatory pouch, or c spermatheca,' which absence relates to 

 there being no intromission in the act of impregnation in Limulus. 



" In the male, the testes are ramified and subreticulate, like the ovaria, and occupy 

 almost an equal extent of the two great cavities of the body. The sperm-ducts open 

 upon a corresponding position of the opercular plate (PI. XXXV, fig. 8jo), their termi- 

 nation being on a smaller but rather more prominent cone of thin yellow chitine, at the 

 apex of which the sperm-tube terminates by a whitish bilabiate orifice (PI. XXXV, 

 fig. 7 b).' n 



Whilst giving the foregoing description of the anatomy of Limulus pohjphemus from 

 the pen of Professor Owen, 2 we must not omit to record that, as early as 1838, Professor 



1 Dr. Packard describes the spermatozoa as having a broad oval body, sometimes contracted before 

 the anterior end, and posteriorly suddenly terminating in a filament about four times as long as the body. 

 "On the Development of the Limulus poly phemus," 4to., ' Mem. Boston Soc. Nat. Hist.,' vol. ii, p. 156. 



2 'Trans. Linn. Soc.,' 1873, vol. xxviii, pp. 459 — 506 (read December 21st, 1871, and January 18th, 

 1872). See also Owen's ' Lectures on the Comparative Anatomy of Invertebrata,' 1st edit., p. 181, 1843, 

 and 2nd edit., pp. 319, 320, 1853. 



