▁Ge ographical ▁Society ▁of ▁London , ▁and ▁received ▁the ▁special ▁comm end ation ▁of ▁the ▁President , ▁Sir ▁R oder ick ▁M urch ison , ▁in ▁his ▁annual ▁address . ▁In ▁ 1 8 7 4 ▁and ▁ 1 8 8 2 ▁McK er row ▁was ▁associated ▁with ▁the ▁British ▁exped itions ▁for ▁the ▁observation ▁of ▁the ▁Trans it ▁of ▁Ven us , ▁ 1 8 8 2 ▁in ▁New ▁Zealand . ▁In ▁ 1 8 8 4 ▁he ▁was ▁elected ▁a ▁Fellow ▁of ▁the ▁Royal ▁Astronom ical ▁Society ▁of ▁London . ▁He ▁was ▁married ▁on ▁ 5 ▁August ▁ 1 8 5 9 , ▁at ▁Fen wick , ▁A yr shire , ▁Scotland , ▁to ▁Miss ▁Mar tha ▁Dun lop . ▁ ▁References ▁ ▁Category : 1 8 3 4 ▁birth s ▁Category : 1 9 1 9 ▁death s ▁Category : Sc ott ish ▁em igr ants ▁to ▁New ▁Zealand ▁Category : New ▁Zealand ▁survey ors ▁Category : B rit ish ▁astronom ers <0x0A> </s> ▁Pol ys ac os ▁is ▁an ▁ext inct ▁genus ▁of ▁multip lac op hor ans ▁( ch it ons ) ▁known ▁from ▁art ic ulated ▁Car bon ifer ous ▁foss ils ; ▁its ▁sevent een ▁shell ▁pl ates ▁are ▁arranged ▁in ▁three ▁rows , ▁with ▁seven ▁iter ated ▁units . ▁It ▁demonstr ates ▁that ▁multip lac op hora ▁are ▁related ▁to ▁modern ▁pol yp lac op hora . ▁It ▁was ▁fr ing ed ▁with ▁a ▁ring ▁of ▁h ollow ▁sp ines ▁res emb ling ▁those ▁of