SKELETO-TEOPHIO TISSUES OF COXAL GLANDS. 145 



the lacunar tissue to a form of reticular connective tissue. 

 Such reticular connective tissue consisting of branched or stel- 

 late cells, the branches being largely skeletal substance, with 

 protoplasmic films overlying them in some instances, but not 

 always — is found in Limulus, though rarely. 



It occurs as " intrusive connective tissue " amongst the 

 nerve-end cells of the central eyes (see this Journal, vol. xxiii, 

 PI. xii, fig. 27 sx), and here and there I have followed the 

 lacunar tissue thinning out to such a reticular condition in 

 other parts, e. g. in the neighbourhood of the great nerve- 

 ganglia. 



I have not found any connective tissue answering to this 

 description in Scorpio, except so far as the branched pigmenti- 

 ferous cells of the central eye agree with it. 



5. Membranous connective tissue of Limulus and Scorpio. 

 In both Limulus and Scorpio delicate ligamentous mem- 

 branes occur here and there, which are formed by a special 

 variety of connective tissue. This tissue is similar to the 

 fibroid skeletal tissue, but differs in this, namely, that the 

 skeletal substance is in the form of a thin, delicately fibrillated 

 lamella, upon which are closely set the protoplasmic cells. 

 These are often much flattened, and spread out on the surface 

 of the membrane so as to constitute an endothelium (PI. IX, fig. 3) . 

 But occasionally certain cells are found at intervals presenting 

 a different character; these are plump, and have abundant 

 granular protoplasm, similar to the cells drawn in PI. XI, fig. 9. 

 These exceptional cells proliferate, and are thrown oft" into the 

 surrounding blood-fluid, probably as normal blood-corpuscles. 

 Such membranous connective tissue forms the limit of the 

 pericardial space in both Limulus and Scorpio. It also forms 

 numerous ligaments, which pass from the pericardial wall to 

 the heart. These ligaments have been described by Gegenbaur 

 in the heart of Limulus^, who points out the mistake of Van 

 der lioeven, who had supposed them to be muscular. 



' Gegenbaur. "Auatoui. Untersuchung eines Limulus." ' Abhandlungen 

 der Naturforsch. GesellscL. iu Halle.' 1858. 



VOL. XXIV. NEW SEK. K 



