JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATES XXVIII AND XXIX, 



Illustrating Professor Lankester's Memoir on " Limulus an 

 Arachnid." 



PLATE XXVIII. 



Fig. 1. — Right pectinate appendage (eightli segment) of Buthus Kochii, 

 anterior face. This figure should be turned so that the pectinate border is 

 upj)erraost, in order to compare with Fig. ] a I', proximal lamella ; Ix., 

 distal lamella (eighteenth). 



Fig. 1 a. — Similar view of the right lamelligerous appendage of the 

 eleventh segment of the same animal for comparison with Fig. 1. /.', proxi- 

 mal lamella; Ix., distal lamella (one hundred and thirtieth; the full number 

 of lamellae are not indicated by the lines in the drawing); m., membrane 

 attaching the axis of the appendage to the superior margin of st., the 

 stigmatic aperture. The appendage is represented as seen when all other 

 structures are removed from the interior of the Scorpion's body, it is re- 

 flected forwards so as to rest with its proper posterior face downwards on 

 the inner surface of the sternite in front of the stigma. The delicate 

 membrane which bounds the pulmonary sac and represents the iavaginated 

 integument is removed. 



Fig. 2. — Right pectinate appendage of Buthus Kuchii, posterior face ; 

 letters as in Fig. 1. 



Fig. 2 a. — Similar view of the right lamelligerous appendage of the 

 eleventh segment of Buthus Kochii, for comparisom with Fig. 2 ; letters as 

 in Fig. 1 a, except b, the canal-like axis which supports the lamellae. 



Fig. 3. — View of the inferior margin of the right pectinate appendage 

 of Buthus Kochii, so placed as to show the imbrication of the lamellae ; 

 letters as in Fig. 1. 



Fig. 3 a. — Similar view of the right lamelligerous appendage of the 

 eleventh segment of Buthus Kochii, for comparison with Fig. 3 ; letters as 

 in Fig. 1 a. 



Fig. 3 b. — Similar view of the ris;ht lamelligerous appendage of the 

 eleventh segment of Limulus poli/phemus for comparison with Fig. 3 and 

 3 a : I.', proximal lamella ; Ix., one hundred and fiftieth lamella ; ex., ex- 

 ternal lappet (exite) of the bifid distal prolongation of the appendage. 



Fig. 4. — View of the sternal surface of the cephalothorax of Limulus 

 polyphemus, from which the five hinder pairs of appendages have been 

 detached, s/"., subfrontal sclerite ; Ch., the. first pair of appendages or 

 chelicerae ; cam., the upper lip or camerostome ; M., the mouth ; pmnt., tlie 

 thoracic promesosternite (representative of pro- and mesosternite as 

 separately developed in the spiders, see woodcut, fig. 9) ; metst., thoracic 

 metasternite or chiiaria, homologous with the pentagonal metasteruite of 

 Scorpio, see woodcut, fig. 8, met. 



