44 PEOF. M. M. HARTOG ON THE 



we can at present go far in this direction, we may at least note that here the intestine 

 is in its hinder part distinctly renal in function, that as the liver is distinctly an out- 

 growth from the anterior digestive part, so Malpighian tubes may be developed (phylo- 

 genetically as they are in fact ontogenetically) as paired outgrowths from the hinder 

 part. Besides this, the basal parts of the limbs are united by a median sternal process, 

 as Lankester noted (" Limulus an Arachnid," Q. J. M. S. xxi. p. 638), though he regarded 

 this in the one group as effected by the outgrowth (or rather downgrowth) of a median 

 sternal process, and not in the other ; but there seems no reason for this distinction *. 



DESCEIPTION OP THE PLATES. 



Note.- — -The great majority of these figures were drawn to' scale with the Oberhauser camera, and 

 scarcely diagrammatized, except by the omission of unimportant details. The striation of the muscles 

 is, however, conventional throughout. The drawings of tbe limbs have been finished for the engraver by 

 Mr. J. Macpberson, and most of tbe others by Miss F. Thorpe, of Cork. To the actual magnification 

 of the drawing I have subjoined the letter of the Zeiss objective under which it was originally made 

 (B F, C i", D $', E £", J tV' imm.). 



The following are the letters used : — 



a., anus ; ap., apodeme ; ap.an., apertor ani ; ap.pm., postmaxillary apodeme ; or., arthrodial 

 (cavity or ridge); at.', antennule; at.", antenna ; b., brain; bl., block of eye; bas., basipodite; car., 

 carapace ; c.f., corneal facet ; co., coupler ; com., commissure ; cox., coxopodite ; ep., epididymis ; epi., 

 cpistoma ; end., endopodite ; ent., free entosternite ; ext., exopodite ; f., furca ; fl., flexor ; g., ganglion ; 

 ff.az., azygos ganglion; h., masticatory book; i., intestine; k., shell-gland; k.o., its opening; 

 /., labrum; lac, lacuna; lap., lappet of paragnatha ; m., muscle; m.ab., abductor; m.add., adductor ; 

 m.ap., apertor; m.ap.an., apertor ani ; m.cons.or., constrictor; m.d., depressor; m.ext., extensor ; m./?., flexor ; 

 m.L, levator; m.oc, occludor; m.pr., protractor; m.pl., pleural; m.r., retractor; mn., mandible; 

 mx., maxilla; mxp. 1 , outer anterior maxilliped ; mxp 2 ., inner or posterior maxilliped; mo., mouth; 

 ii. , nerve, nerve-cord; n.az., azygos nerve; n.fr., frontal nerve; n.fr.sup., superior frontal nerve; 

 n.fr.L, inferior frontal nerve ; m.m., motor nerve ; n.pl., pleural nerve (to side-walls of body) ; n.sens., 

 sensory nerve; n.th., thoracic nerve ; o., outer ; oc, ocellus ; oc J., lateral ocellus ; oc.v., ventral ocellus ; 

 od., oviduct ; oe., oesophagus ; ov., ovary ; p.. palp or palpiform process ; pc, pore-canal ; pg., paragnatha ; 

 jjI., pleuron ; p.o.b., postoral bar; p.p., pectinate process; pr.v., prerectal valve; r., rostrum; re., 

 rectum; ri., ridge; s., stomach; sa.g., salivary gland ; sa.p., salivary pore; sp.d., sperm-duct ; spp., pore 

 of spermatheca; su.a.p., supra-anal plate; sp.th., spermatheca ; St., sternal plate; t., tooth ; te., testis; 

 th., thoracic segment or appendage; u., uterus ; v.d., vas deferens; v.e., vas efl'erens; ve.s., vesicula 

 seminalis ; vu., vulva. 



Plate I. 



Figs. 1-10 are all magnified 150 diameters : C. 

 Fig. 1 . Right antennule of female. 

 Fig. 2. Right antennule of male. 

 Fig. 3. Antenna. 

 Figs. 4, 4 a. — 4. Left mandible, ventral aspect ; 4 a, posterior aspect. (The full length of the seta- 



of the palp is not drawn.) 

 Figs. 5, 5 a. — 5. Left maxilla, posterior aspect ; 5 a, ventral aspect. 



* I leave this passage as it was written in 1SS4 ; but I am more and more inclined to accept the view that the 

 Arachnida are rather connected with the Arthrostniea. Feb. 1888. 



