AND EMBRYOLOGY OF LIMULUS. 41 



Owen. Anatomy of the King Crab. (Limulus polyi^hemus Latr.) By E. Owen. London, 1873. Trans. 

 Linn. Society, London. 5 plates. 4". pp. 50. 



Lankestbk. Mobility of the Spermatozoids of Limulus. By E. R. Lankester. Quart. Journ. Micr. 

 Science. Oct., 1878. pp. 453-454. 



See also Strauss-Dtirckheim's Traite d'Anatomie Comparative. 1842. 



Owen's Lectures on the Invertebrate Animals. 1843-1855. 



Woodward's papers on Merostomata. Palaeontol. Society. 1866-1878. 



Huxley's Anatomy of the Invertebrate Animals. 1877. 



W. Grenacher's XJntersuchungen iiber das Sehorgan der Arthropoden. 1879. 



EXPLANATION OF THE PLATES. 



Plate I. 



Fig. 1. Under side of a Limulus, a little over two inches long without the spine, injected to show the 

 abundance of the arterial twigs in the limbs and caudal spine as well as the body. The injection was made 

 at Penikese by the late Edwin Bicknell. J. S. Kingsley, del. 



Fig. 2. Camera lucida drawing of a living larva, showing the circulation of the blood-corpuscles in the 

 right under-side of the abdomen and on the left first abdominal limb. Author, del. 



Fig. 3. Camera lucida drawings, showing the actual course taken by the blood corpuscles in the first 

 abdominal appendage of the same larval Limulus. The arrows show the direction of the currents of blood, 

 with the corpuscles ; the blood passing from the heart down along the inner side of the appendage, and 

 passing by tortuous, irregular courses around by the outside, back along the base, and returning to the peri- 

 cardial chamber through the venous opening. This mode of circulation is much as we have seen take place 

 in the amphipodous Crustacea, Author, del. 



Plate II. 



Fig. 1. Transverse section of adult male Limulus, natural size, through the proventriculus \_pr'\, showing 

 the cone [c], the oesophagus [oe], and the brain [br] ; a, aorta, or frontal artery ; col, collective venous 

 sinus. From a drawing made for the author at Penikese by P. Roetter. 



Fig. 2. Section through the cephalothorax in front of the heart, brain, and first pair of gnathopods ; 

 m, muscles. J. S. Kingsley, del. 



Fig. 3. Section through the cephalothorax behind the first pair of gnathopods ; ht, heart ; m, great longi- 

 tudinal adductor muscle ; cp, supraneural cartilaginous plate protecting the central nervous system. The 

 latter not shown. J. S. Kingsley, del. 



Fig. 4. Transverse section through the abdomen, showing the second abdominal, or first respiratory, foot ; 

 ht, heart, beneath which is the intestine ; b, origin and middle of branchio-cardiac veins, which carry the 

 blood from the limb to the heart. J. S. Kingsley, del. 



Plate III. 



Fig. 1. Longitudinal section through a Limulus about two inches long, exclusive of the caudal spine ; 

 ht, heart ; m, mouth, leading by the oesophagus to the proventriculus [pr] ; cone, proventricular cone ; st, 

 stomach ; in, intestine ; a, anus ; br, brain, or supraoesophageal ganglion, behind which is a part of the 

 oesophageal ring [oe. r'] ; ng, ganglionated cord ; ct, supraneural cartilaginous plate ; enlarged about twice. 



Fig. 2. Longitudinal section through the larva of Limulus on one side of the heart and digestive tract, 

 passing through the brain and cephalothoracic ganglia ; br, brain ; the six other ganglia [1-6] separate from 

 one another, and afterwards consolidate to form the " oesophageal ring" ; 1, the first ganglion which supplies 

 a pair of nerves to the first pair of gnathopods. [Compare plate 4, fig. 7, gn.'\ 



